Monday Mar 23, 2015

Renaming tables with MySQL Enterprise Backup 3.12.0

Introduction

MySQL Enterprise Backup 3.12.0 (MEB) introduces a new feature for restoring an InnoDB table from a backup. Now it is possible to rename the table during restore. This is useful when the user wants to restore a table from a backup without overwriting the existing version of the table in the database.

The following example illustrates how the renaming feature could be used.  Suppose that the DBA has deleted three rows from a table T1 by mistake and he now wishes to get them back from a backup. He wants to leave the database online and to restore the 3 deleted rows from a TTS backup (a backup created with the --use-tts option) that contains the table T1.  He can do this with this feature in three steps:

  1. He restores with MEB the table T1 from a TTS backup renaming it to T2.

  2. He uses MySQL client to issue SQL statements to copy the 3 mistakenly deleted rows from the table T2 to the table T1.

  3. He drops the table T2.

Now the accidentally dropped rows have been restored and the restore took place when the MySQL server was online and the restore did not disturb the normal operation of the server in any way.

User Interface

The command-line interface for restore is extended with the --rename option that specifies a mapping of from the old name to the new name. The --rename option has the following syntax:

--rename="OLD-NAME  to  NEW-NAME

The OLD-NAME and NEW-NAME are either fully-qualified tablenames of the form DB.TABLE, or tablenames without the database part. The OLD-NAME must match the name of the table selected for restore.  

Example 1:

A sample command-line for restoring the table test.abc  to  test.abc_new:
$ mysqlbackup --include-tables="test\.abc"
              --rename="abc TO abc_new" 
              ...
              copy-back
In this example we assume that the backup contains several tables. Therefore, we have to specify a single table (test.abc) with the --include-tables option.

Example 2:

A sample command-line for restoring the table db.abc  to  db2.abc:

$ mysqlbackup --include-tables="db\.abc"
              --rename="abc to db2.abc" 
              ...
              copy-back

Note that if the database db2 does not exist, the restore will create it.

Example 3: 

Below is an excerpt of the printouts MEB produces when a table is renamed during restore using the command-line from Example 1: 


$ mysqlbackup --backup-dir=/full-backup --include-tables="test\.abc" --rename="abc TO new_abc" copy-back
MySQL Enterprise Backup version 3.12.0 Linux-3.2.0-69-generic-i686 [2015/01/22] 
Copyright (c) 2003, 2014, Oracle and/or its affiliates. All Rights Reserved.
 mysqlbackup: INFO: Starting with following command line ...
 /home/pekka/bzr/meb-trunk/src/build/mysqlbackup 
        --backup-dir=/full-backup --include-tables=test\.abc 
        --rename=abc TO new_abc copy-back 
 mysqlbackup: INFO: 
IMPORTANT: Please check that mysqlbackup run completes successfully.
           At the end of a successful 'copy-back' run mysqlbackup
           prints "mysqlbackup completed OK!".
150312 11:17:53 mysqlbackup: INFO: MEB logfile created at /full-backup/meta/MEB_2015-03-12.11-17-53_copy_back.log
 mysqlbackup: INFO: MySQL server version is '5.6.11'.
 mysqlbackup: INFO: Got some server configuration information from running server.
...
 mysqlbackup: INFO: Creating 14 buffers each of size 16777216.
150312 11:17:53 mysqlbackup: INFO: Copy-back operation starts with following threads
		1 read-threads    1 write-threads
150312 11:17:53 mysqlbackup: INFO: Creating table: test.abc.
150312 11:17:53 mysqlbackup: INFO: Copying /full-backup/datadir/test/abc.ibd.
150312 11:17:53 mysqlbackup: INFO: Completing the copy of all non-innodb files.
150312 11:17:54 mysqlbackup: INFO: Importing table: test.abc and renaming it to test.new_abc.
150312 11:17:55 mysqlbackup: INFO: Analyzing table: test.new_abc.
150312 11:17:55 mysqlbackup: INFO: Copy-back operation completed successfully.
150312 11:17:55 mysqlbackup: INFO: Finished copying backup files to '/sqldata/tts-5.6'
mysqlbackup completed OK! 

Limitations

Renaming works only when restoring a single table from a TTS backup (a backup created with the --use-tts option). If the backup contains multiple tables, then a single table should be specified for restore with the --include-tables and --exclude-tables options. 

Thursday Mar 19, 2015

Distributing innodb tables made simpler!

With the support for cloud backups in MEB, distributing innodb tables across multiple MySQL instances has become easier.

1. Backup - take a cloud(Amazon S3) backup of the tables to be shared using the --use-tts=with-full-locking option.

./mysqlbackup \
--host=localhost --user=mysqluser --protocol=TCP --port=3306 \
--cloud-service=s3 --cloud-aws-region=us-east-1 \
--cloud-bucket=mebbackup –cloud-object-key=items.img \
--cloud-access-key-id=<access-key> --cloud-secret-access-key=<secret-key> \
--include-tables=^mycompany\.items.* --use-tts=with-full-locking \
--backup-dir=/tmp/bkups/backupdir --compress --backup-image=- \
backup-to-image


(here the regex used will backup the tables whose name match “items*” in the database “mycompany”.)

2. Change Permissions - from the Amazon S3 (web) console, change the permissions of the backup file.

For a restore by users without S3 accounts, the file “Open/Download” permissions should be granted to “Everyone”. To restrict restore only to users with valid S3 accounts grant “Open/Download” permissions for “Authenticated Users”.

3. Restore - any number users(/MySQL applications) from anywhere (with/without S3 accounts) can use MEB to restore the new tables into a running MySQL instance.

./mysqlbackup \
--host=localhost --user=mysqluser --protocol=TCP --port=3306 \
--cloud-service=s3 --cloud-aws-region=us-east-1 \
--cloud-bucket=mebbackup –cloud-object-key=items.img \
--backup-dir=/tmp/bkups/cpbackdir --uncompress \
--datadir=/home/mysql-5.6/datadir --backup-image=- \
copy-back-and-apply-log


(options --cloud-access-key-id=<access-key> --cloud-secret-access-key=<secret-key> needed if “Open/Download” permissions are set for “Authenticated Users”)

Make sure the tables being imported do not exist in the target database. This operation is same as importing tables from a backup taken with --use-tts option.

4. Done!

Monday Sep 15, 2014

MEB copies binary logs and relay logs to support PITR and cloning of master/slave

With MySQL Enterprise Backup(MEB) 3.9.0 we had introduced full instance backup feature for cloning the MySQL server. Now with MEB 3.11.0 we have enhanced the feature by copying all the master-slave setup files like MySQL server binary logs(will be referred as 'binlogs'), binary log index files, relay logs of slave, relay log index files, master info of slave, slave info files. As part of full instance backup, copying of binlog files is default behavior MEB-3.11.0 onwards. DBA should be aware of the fact that current full instance backup is bigger than the backups with old MEB's.

As every event on MySQL production database goes as a entry to binlog files in particular format, binlog files could be huge. Backing of huge binlog and/or relaylog files should not impact the performance of MySQL server. Hence, all the binlog files, except the current binlog used by server, are copied just like the innodb .ibd files without locking tables. Binlog files currently being used by server and added after backup started, are copied during read the lock which is acquired by MEB for copying meta files and redo logs.

DBA gets the following benefits:

---------------------------------------------

1) Direct cloning of  master and slave possible from backup

Earlier DBA had to copy binlog files manually in order to setup  master/slave. Now, MEB 3.11 by default copies all the files including the global variables needed for setting up master-slave. Hence DBA can clone master or slave with the same state of backed-up server.

Now, DBA need not to use --slave-info option to copy the binlog info for setting up the slave after restore. By copying master and slave info files,  DBA can fetch the information of up to which master binlog position,  slave SQL thread has executed and IO threads has read etc. With this information along with relay logs, binlogs, DBA can easily setup slave from backed-up slave content

2) Backup of binary logs helps in Point In Time Recovery (PITR)

First let us understand what is PITR by above example. Consider DBA has taken full backup on Sunday(assume date as 14-09-2014), and incremental backups on Tuesday(date as 16-09-2014), Thursday(date as 18-09-2014). It means DBA can only restore database up to full backup or incremental backups in other words database can be restored either up to Sunday or up to Tuesday, Thursday,  but not in between let say Monday or Wednesday. Because backup is just a snapshot of data when it was taken. Hence backup taken once can't be restored in between without change log.  That's where binlog helps in restoring to a certain point of time, which is called Point-In-Time-Recovery(PITR). As binlogs captures all the events of a server with timestamps. Therefore to restore in between DBA need to have base data i.e. full backup and incremental binlogs.

Let's look at our example, below are the points to recover server to Wednesday 12 PM(assume date as 17-09-2014)
a) Restore the backup up to latest backup before PITR time(Here, restore Tuesday's incremental)
b) Get the SQL statements using below mysqlbinlog command up to PITR from the immediate next incremental binlogs(Here get SQL statements up to Wednesday from Thursday's incremental binlogs of binlog.000005, binlog.000006, binlog.000007)

mysqlbinlog --start-datetime=<latest backup time before PITR time> \
         --stop-datetime=<PITR point> \
         <incremental binlogs from immediate next backup>  > <SQL file>

For our above example, the command is
mysqlbinlog --start-datetime="2014-09-16 12:00:00" \
         --stop-datetime="2014-09-17 12:00:00" \
         binlog.000005 binlog.000006 binlog.000007  > mysql_PITR_restore.sql

Read Point-in-Time (Incremental) Recovery Using the Binary Log for more details about PITR using Binary logs.

c) Execute the SQL statements obtained on the restored server, server is restored to PITR point


3) Backing up relay-logs from slave server helps avoiding unnecessary pull of logs from master once it is restored

Let us understand this by an example

Slave has 1 relay log with master binlog positions from 1 to 100

SQL thread at slave reads from relaylog and apply events on slave. Now assume SQL thread currently executed statements 1 to 20 and 21 to 100 are yet to be executed.

If DBA takes backup without copying relay log, when he/she restores the backup as slave, it asks master from the binlog position 21. So restored slave need to pull the logs of binlog position 21 to 100 from master. More network I/O needed as usually slave is on different machine.

As MEB takes backup of relay log, slave can avoid pulling the logs for binlog positions 21 to 100. Now restored slave asks master from binlog positions 101 onwards. This way slave don't pull logs from master which are present in slave backup, there by reducing network I/O which is costly than disk I/O.

Unlike binary logs, relaylogs are mostly deleted automatically once applied by SQL thread, as a result few relay logs exist at any point of time. So all the relay logs are copied for all the backup types full, incremental, partial without major impact on backup size and time.

4) Copied binary logs remains consistent with the backup data

Earlier DBA had to copy binlog files manually in order to setup master/slave. Data files are copied by MEB and binlogs are copied by DBA at two different times, so there is a possibility of binlog files not consistent with the backed-up data.

Lets consider following example:
1. MEB takes backup of the server without binlogs at 1 PM
2. DBA has copied binlogs from the server at 1:30 PM
From 1 PM to 1:30, lets say 100 events logged in binlogs

Now to use these binlog files, DBA has to either execute 100 events on server or have to remove 100 events from binlog files.

Consider another example:

1. DBA has copied binlogs from the server at 1:30 PM
2. MEB takes backup of the server without binlogs at 2 PM
From 1:30 PM to 2 PM, lets say 100 events went into backup data

Now DBA has to copy the missing binlog files again from the running server.
With MEB 3.11.0 onwards, binlogs and the data are copied at the same time, so they are consistent with each other.

Options to avoid binlogs/relay logs:
--------------------------------------------------
If DBA is not concerned about backing up binlog files then he/she can use --skip-binlog and --skip-relaylog to skip relay log files in backup. It is advisable to use these options if he/she don't plan to clone server or want PITR.

For Master, to skip only binlogs:
./mysqlbackup --skip-binlog --backup-dir=back_dir --socket=server_sock backup

For Slave, to skip relay-logs
./mysqlbackup --skip-relaylog --backup_dir=back_dir --socket=server_sock backup

For Slave which is also a master, to skip both binlogs and relay logs
./mysqlbackup --skip-binlog --skip-relaylog backup_dir=back_dir --socket=server_sock
 backup


Options for offline backup:
------------------------------------
MEB also supports offline backup. In order to copy binlog and/or relaylog, MEB searches for default values of log-bin-index(default: host_name-bin.index), relay-log-index(default: host_name-relay-bin.index), relaylog-info-file(default: relay-log.info), master-info-file(default: master.info) at default location that is in server's 'datadir'. And if MEB finds those files then it successfully backs up those files. In case those files are configured with different values, DBA need to provide --log-bin-index = PATH, --relay-log-index = PATH, --relaylog-info-file = PATH, --master-info-file=PATH options to MEB in order to copy them.

Conclusion:
-----------------
To enrich the full instance backups that MySQL Enterprise Backup has been performing since release 3.9.0, all the replication setup files are included as part of all the backups in 3.11.0. With these files as well as all the global variables, plugin details, MEB now takes the responsibility of giving all the details to DBA for cloning any server. Read MEB 3.11.0 documentation for more details and many other great features.

Friday Sep 05, 2014

Selective Restore of InnoDB Tables with MySQL Enterprise Backup 3.11

Introduction

Sometimes the best way to repair data issues and problems within a MySQL database is to restore only some of the tables from a backup. For example, suppose that some data was accidentally deleted from one table due to a software error, then the easiest way to recover the lost data might be to restore only one table from a backup. Previously this kind of partial restore was not supported by MySQL Enterprise Backup (MEB). However, MEB 3.11 introduces support for selective restore from backups created with the --use-tts option (or TTS backups).

TTS backups are backups that are created with the transportable tablespaces feature of InnoDB. These backups consist of InnoDB tables that have their own tablespaces (.ibd files). A TTS backup can be restored only to a running server, because MEB needs the server to execute SQL statements during the restore.

In selective restore the user specifies the names of the tables to be restored from a TTS backup using the --include-tables=REGEX1 or the --exclude-tables=REGEX2 option (or both), where REGEX1 and REGEX2 denote regular expressions. A table is restored from a backup if the fully-qualified name of the table (that is, a name of the form DATABASE.TABLE) matches REGEX1 and does not match REGEX2.

Selective restore does not overwrite any existing tables at the server. So, the user should first delete (or rename) all those tables at the server that are going to be restored from a backup.

Examples

The following examples demonstrate how selective restore can be used. Suppose there is a database called "color" with five InnoDB tables that have their own tablespaces:

  blue1
  blue2
  dark_blue
  light_blue
  red

We have created a TTS backup of the "color" database with the following mysqlbackup command

$ mysqlbackup --include-tables="^color\." --use-tts --backup-dir=/full-backup 
              backup

and prepared the backup in the "/full-backup" directory with

$ mysqlbackup --backup-dir=/full-backup apply-log

Let's now assume that the table "red" is now broken and we wish to restore it from the backup. We must first delete the table by issuing a DROP TABLE statement with the MySQL client. After removing the table we can restore it from a TTS backup as follows

$ mysqlbackup --backup-dir=/full-backup --include-tables="^color\.red$" 
              copy-back

Here we specified a single table with the --include-tables option.

In the next example we work with the same "color" database as above, but we make a backup in a single file

$ mysqlbackup --include-tables="^color\." --use-tts --backup-dir=/full-backup 
              --backup-image=/backups/image backup-to-image

The created backup image contains all five InnoDB tables of the "color" database.

Now we wish to restore the tables "blue2", "dark_blue" and "light_blue" from the backup image. But before we can do this, we have to drop these tables at the server. After that the following mysqlbackup command restores these three tables.

$ mysqlbackup --backup-image=/backups/image --backup-dir=/full-backup 
              --include-tables="^color\..*blue.*$" --exclude-tables="blue1" 
              copy-back-and-apply-log

We have specified the tables to be restored with the --include-tables and --exclude-tables options illustrating the power of regular expressions in specifying the set of tables to be restored.

If only a few tables are to be restored, then usually the easiest way to do this is to specify these tables with the --include-tables option. The mysqlbackup command shown below restores the tables "blue2" and "dark_blue" from a single-file backup.

$ mysqlbackup --backup-image=/backups/image --backup-dir=/full-backup 
              --include-tables="^color\.blue2$|^color\.dark_blue$" 
              copy-back-and-apply-log

A user more familiar with regular expressions might want to replace the value for the --include-tables option in the example above with

--include-tables="^color\.(blue2|dark_blue)$"

which is an equivalent but shorter regular expression.

Working with multiple InnoDB datafile formats

There are currently two InnoDB datafile formats - the older Antelope format and the newer Barracuda format that offers features not available with the Antelope format. If either the server or the backup contain InnoDB tables in different formats, then this might cause problems for selective restore. Fortunately, these problems can be solved by invoking the restore command with suitable options.

To understand this problem we have to look at how InnoDB database engine creates new tables.  When an InnoDB table that has its own datafile (.ibd file) is created at the server, the format of the InnoDB datafile is determined by the CREATE TABLE statement and the value of the innodb_file_format system variable. If the CREATE TABLE statement specifies features that require the Barracuda format and the value of the innodb_file_format system variable is also "Barracuda", then the datafile is created in Barracuda format. But if the value of innodb_file_format is "Antelope", then the format of the datafile will be "Antelope" even if the CREATE TABLE statement actually specified features requiring the Barracuda file format.

During selective restore MEB issues first a CREATE TABLE statement (obtained from the backup) to create an empty table at the server. After this, the original (empty) datafile is replaced with the datafile copied from the backup. But this step fails, if the original datafile and the datafile in the backup are not in the same format. This happens, for example, if the datafile in the backup is in Barracuda format, but the value of the innodb_file_format system variable is "Antelope" when selective restore is attempted.

This problem can be solved by specifying the --force option for the mysqlbackup command-line invoking selective restore. With the --force option, mysqlbackup changes temporarily the value of the innodb_file_format system variable for each table that is restored. This quarantees that selective restore succeeds regardless of the format of InnoDB tables in the backup and the value of innodb_file_format, provided, of course, that other users do not change the value of innodb_file_format during the restore.

Warnings

The integrity of the database is not enforced by MEB. Instead, it is the user's responsibility to keep track of the foreign-key constraints on the restored data.

Limitations

Selective restore is not possible from TTS backups created in the full-locking mode (specified with --use-tts=with-full-locking). Selective restore works only with TTS backups created in the minimum-locking mode (--use-tts=with-minimum-locking), which is the default mode for TTS backups.

Thursday Sep 04, 2014

Optimistic Backup

Introduction 

MySQL Enterprise Backup (MEB) is a highly efficient tool for taking backups of your MySQL databases. In the 3.11.0 release we are taking that one step further by introducing a new concept called "optimistic" backup. Optimistic backup leverages the patterns we saw frequently especially as related to very large databases.

For backups the goals are:
1 - Quality and Consistency - the backup and more importantly the restore just "works"
2 - Size, time, and overhead - like in the game of golf - low score wins - for backups and for
     restores.
3 - Flexibility – It’s not always one size fits all - whether how the backup is run, where it goes,
     how it is recovered.

With optimistic backup - we look at mostly the read aspects of your database to enable us to create a backup that is smaller, faster to backup, faster to restore, and has less overhead when running, but still remains consistent. As we said earlier “optimistic” is not for all databases. Those that benefit the most are databases where modifications(insert/updates/deletes) are focused on a minority of the tables, and store a great deal of data will benefit the most. In our tests (details below) mean time to restore reduced 18%, resulting from a 60% reduction in the size of the redo log that is applied on recovery. What follows is the deals on how this works. We also want to thank the DBAs who provided great feedback and details on their database characteristics during our development of this new feature.

Optimistic Backup

Whole idea is summarized in following two steps.

1.  Divide the InnoDB tables into two groups. In the first group are those tables that are unlikely to be modified during the backup, and in the second group are all the other tables. MEB is optimistic about the first set of tables as they are unlikely to be modified during backup operation hence these tables are termed as optimistic tables and backup operation is named after them as "optimistic backup". Tables in the second group are likely to be modified during backup operation hence are termed as optimistic busy tables.

2.  Split full backup operation into two phases. In the first phase of the backup, tables from the first group are copied to the backup without locking the MySQL server instance. In the second phase tables from second group are copied similar to normal backup i.e.  All InnoDB tables from second group and tables from the first group that have modified since the backup started are copied to backup, then MySQL server instance is locked to copy remaining files. First phase always excludes the undo/redo logs, system table space files and other meta files because these are most likely to be modified. Since optimistic tables are copied in the first phase hence it is called optimistic phase and second phase is called normal phase. 

How to trigger Optimistic backup

Following two new options have been introduced to trigger optimistic backup. Provide either of these two or both options to enable optimistic backup.

optimistic-time

This option specifies the cut-off date-time to identify tables to be skipped in first phase. In other words, tables modified before the specified date-time (i.e. optimistic tables), are copied in first phase and tables modified after specified date-time value (i.e. busy tables), are copied in second phase.  Following date-time formats are supported by this option- 

• <Number><unit> - A valid integer number according to its unit. Supported units are years, days, months, hours and minutes. 

For example: ‘--optimistic-time=1years’ means tables modified one year before the backup starts to be copied in first phase. In other words tables modified in last one year from the backup starts to be copied in second phase.

• Date-time - It can be specified in different formats as:  YYMMDD, YYYYMMDD, YYMMDDHHMMSS, YYYYMMDDHHMMSS, YY-MM-DD, YYYY-MM-DD, YY-MM-DD HH.MM.SS,   and YYYYMMDDTHHMMSS where T is a character. 

For example - 16th May 2014 can be specified as 140516 or 20140516. Therefore ‘--optimistic-time=20140516’ means tables modified before this time will be copied in first phase.

• now - This is the default value of this option. If no value is specified against this option then MEB will assign “now” as default value. Internally MEB keeps backup start time as optimistic time and use the same throughout the backup operation. With this option all InnoDB tables are be copied in the 1st step.

For example:   --optimistic-time=now   OR --optimistic-time

optimistic-busy-tables

This option specifies the InnoDB tables (i.e. busy tables) to be skipped in the first phase. It requires regular expression as specified in the POSIX 1003.2 standard, similar to – include/exclude-tables=REGEX option. This option expects fully qualified names of database objects, i.e. database_name[.table_name] in regular expression. Tables that match the REGEX criteria will be skipped in the first phase and copied in the second phase. This option can co-exist with 'optimistic-time', 'include-tables' and 'exclude-tables' options. These options will get precedence in ascending order as following 

Include/exclude-tables > optimistic-busy-tables > optimistic-time

Include/exclude-tables options gets higher precedence over optimistic-busy-tables option.

For instance - if same table is specified in the –exclude-tables and –optimistic-busy-tables then that table is not copied at all. 

optimistic-busy-tables gets higher precedence over optimistic-time option. 
For instance - if a table ‘user’ has modified time of ‎ “04/15/‎2014 ‏‎2:19:32”. If --optimistic-busy-tables=^test.user --optimistic-time=04142014 values are specified then file test/user.ibd is not be copied in first step because optimistic-busy-tables value matches the REGEX so test.user.ibd is not evaluated by optimistic-time option.

Using Optimistic backup

Following are samples of command line options need to be specified to perform different types of optimistic backups. 

1. Normal Backup with optimistic backup options

  >mysqlbackup.exe --backup-dir=D:\backup --optimistic-busy-tables="^db2\.t1+" backup

  >mysqlbackup.exe --backup-dir=D:\backup --optimistic-time backup

2. Compress Backup with optimistic backup options

 >mysqlbackup.exe --backup-dir=D:\backup --compress-method=lzma
   --optimistic-busy-tables="^db2\.t1+" backup 

 >mysqlbackup.exe --backup-dir=D:\backup --compress-method=lzma --optimistic-time=now
   backup 

3. Compress Image Backup with optimistic backup options

 >mysqlbackup.exe --backup-dir=D:\backup --compress-method=lzma
  --backup-image=D:\backup.img  --optimistic-busy-tables="^db2\.t1 +" backup-to-image

 >mysqlbackup.exe --backup-dir=D:\backup --compress-method=lzma
  --backup-image=D:\backup.img  --optimistic-time="2014-08-27 13.25.00" backup-to-image

4. Compress and encrypted Backup with optimistic backup options

 >mysqlbackup.exe --backup-dir=D:\backup --compress-method=lzma
   --backup-image=D:\backup.img --encrypt --key=xxxxxxxxx
   --optimistic-busy-tables="^db2\.t1 +" backup-to-image

 >mysqlbackup.exe    --backup-dir=D:\backup --compress-method=lzma
   --backup-image=D:\backup.img --encrypt --key=xxxxxxxxx
   --optimistic-time=20140827T132500 backup-to-image

5. Partial Backup with optimistic backup options

 >mysqlbackup.exe --backup-dir=D:\backup --optimistic-time=25days
   --include-tables="^db2+"  backup

 >mysqlbackup.exe --backup-dir=D:\backup --optimistic-busy-tables="^db2\.t1+"
   --include-tables="^db2+"  backup 

 >mysqlbackup.exe --backup-dir=D:\backup --optimistic-busy-tables="^db2\.t1+"
   --optimistic-time=10Months --include-tables="^db2+"  backup

Troubleshooting optimistic backup

If optimistic backup is triggered then MEB prints INFO messages in log in following order to know when each phase of backup started and finished. 

First phase of optimistic backup started 

…….............

…….............

First phase of optimistic backup completed successfully

Second phase of optimistic backup started

……….........

……….........

Second phase of optimistic backup completed successfully

Turn on --trace option for more diagnostic information in logs. Internally MEB converts optimistic-time value to an epoch time stamp and compares the same with the InnoDB files’ modification time. 

With increased trace levels we see optimistic-time, backup start time and InnoDB table modification time in form of the epoch time stamp. We can easily convert these epoch time stamps in human readable time either using SQL query or through some external tools, for instance epoch converter.

Choose values of Optimistic backup options wisely

It's imperative to choose the suitable values of above options in order to maximize the gain from optimistic backup. Optimistic backup targets large databases in which only a few tables are modified frequently. DBA can find out such tables or time since when most of those tables have modified, either by profiling database or directly from file system. If such tables are identified then those tables can be specified in optimistic-busy-tables option. If duration, since when only small percentage of tables are modified, is identified then that date-time can be specified in optimistic-time option.  

Imagine the value of optimistic-busy table option is not chosen carefully then chances are that some optimistic tables might be copied in second phase which ideally should have been copied in first phase only, as a result redo log size will increase and hence overall backup time.
Similarly if the value of the optimistic-time option is not chosen carefully then chances are that some busy tables might be copied in first phase which ideally should have been copied in second phase only. In second phase those stale tables are copied again, as a result overall backup time will increase. In such cases for image backup, busy tables will be copied in both phases hence disk space and backup time both will increase. 

If only a few tables less in size (e.g. ~2% of the total size of the the database) will be modified during backup time then default value of optimistic-time 'now' should serve the purpose. In this case only those a few tables will be copied twice. 

Performance tests

In our internal tests we created a 1.2 TB of DB which had 25 tables initially. We created 3 tables and updated them continuously until backup operation completed successfully. We observed ~60% reduction in redo log file (ibbackup_logfile) size and ~18%  reduction in overall backup (backup + apply log) time compared to normal backup operation. Of course these numbers highly depends on the hardware, CPU load and types of DDL being executed. Therefore a user might experience better or poor performance than the numbers shared here. Purpose to share the number is to show that if options are specified correctly then optimistic backup performs better compared to normal backup.

Conclusion

The optimistic backup isn't for all cases, but for many it will have significant advantages and benefits over a typical full backup. So we hope you'll give it a try and provide us feedback on how it works for your environment. We shall also follow-up with additional queries and scripts to help you easily determine how values to set for the optimistic backups, although we suspect that many DBAs likely already know their data so well they won't need these. Never forget, good backups, and more importantly successful and timely recovery is the top priority for a DBA. For more details and usage samples, please refer MEB Manual.

Tuesday Jul 01, 2014

Streaming backups onto the Cloud Storage


MySQL Enterprise Backup(MEB) has been widely used as the most efficient tool to take backups of huge databases. The storage of backups can be done on-premises – viz, local hard disk, external hard disk drives, network mounted disk. MEB can also stream backups to tape by supporting different Media Management Software like Symantec NetBackup, EMC2 and Oracle Secure Backup. Streaming of backups can also be done using 'ssh' to another machine.

As data keeps growing, instead of expanding the storage, database users are choosing to rely on the growing trend which is the Cloud Storage.

A few facts about Cloud Storage:

1. Offers off-premises storage with AAA(Anytime, Anywhere Access)
2. Sharing of data to make a collaborative effort.
3. Highly fault tolerant, durable and scalable and secure.
4. Cost-effective

To the benefit of our MySQL database users, Mysql Enterprise Backup (MEB) has come up with the support for taking their backups and storing directly on the cloud.

MEB 3.10.2 provides this great feature of storing image backups on the cloud with its simplified command-line options. The backups can be restored from the cloud as well.

How does it work?


    MEB streaming backup from Remote Machine /  EC2 Instance to Amazon S3      

As illustrated in the picture, MEB can be hosted along with Server either on a remote machine or on the Amazon EC2 instance to take backup of MySQL databases/tables which will be stored in Amazon S3.

The list of cloud options introduced are:

  • --cloud-service : Cloud service for data backup or restoration. Currently, only the Amazon S3 service is supported, and “s3” is the only value mysqlbackup accepts for this option.
  • --cloud-bucket : The storage bucket on Amazon S3 for the backup image.
  • --cloud-object-key : The Amazon S3 object key for the backup image.
  • --cloud-access-key-id : AWS access key ID for logging onto Amazon S3.
  • --cloud-secret-access-key : AWS secret access key that goes with the AWS access key id used in --cloud-access-key-id.
  • --cloud-aws-region : Region for Amazon Web Services that mysqlbackup accesses for S3.
  • --cloud-trace : Print trace information for cloud operations. It works independently of --trace, which specifies the trace level for the non-cloud operations of mysqlbackup. Any non-zero value for the option enables the trace function. Default value is “0.”
  • --cloud-proxy=proxy-url:port : Proxy address and port number for overriding the environment's default proxy settings for accessing Amazon S3.


Lets dive into the MEB command-line with the options to be used for cloud storage.

For taking a simple image backup of the whole server:

./mysqlbackup --cloud-service=s3 --cloud-bucket=mebtest --cloud-object-key=cloud_image.bi --cloud-access-key-id=accessKeyId --cloud-secret-access-key=******** --cloud-aws-region=awsRegion --backup-dir=/backuptmp --backup-image=- backup-to-image  

For taking a image backup of selective tables:

This is very useful to allow access to specific table(s) to other users. As you are aware, the users can restore these tables onto their running server.

./mysqlbackup --cloud-service=s3 --cloud-bucket=mebtest --cloud-object-key=cloud_image.bi --cloud-access-key-id=accessKeyId --cloud-secret-access-key=******** --cloud-aws-region=awsRegion –include-tables=db1.tab1 --use-tts=with-full-locking --backup-dir=/backuptmp --backup-image=- backup-to-image  

MEB also supports compressed, encrypted and incremental image backups onto the cloud.

For example, to perform an encrypted image backup, the command-line is:

./mysqlbackup --cloud-service=s3 --cloud-bucket=mebtest --cloud-object-key=cloud_image.bi --cloud-access-key-id=accessKeyId --cloud-secret-access-key=******** --cloud-aws-region=awsRegion –encrypt –key-file=encryptKeyFile --backup-dir=/backuptmp --backup-image=- backup-to-image  

All operations supported for non-cloud image backups can be performed.
Here goes the list:

extract
image-to-backup-dir
validate
copy-back-and-apply-log

The image stored on the cloud can be directly restored onto a (running) server.

For restoring the selective image backup into a running server:

./mysqlbackup –defaults-file=/backuptmp/backup-my.cnf --cloud-service=s3 --cloud-bucket=mebtest --cloud-object-key=cloud_image.bi --cloud-access-key-id=accessKeyId --cloud-secret-access-key=******** --cloud-aws-region=awsRegion --backup-dir=/restoretmp --backup-image=- --datadir=/datadir copy-back-and-apply-log  
Note: This is the image backup taken with –use-tts option.

For more options and usage samples, please refer MEB Manual.

Thus MEB helps the user to take backups and stream it to cloud using simple command-line WITHOUT the need for any external tool or script.

Tuesday Apr 29, 2014

Cloning a slave using Mysql Enterprise Backup on a GTID enabled server

MySQL 5.6 introduced a new feature called GTID (Global Transaction IDentifier) support in Replication. For every transaction that is committed on to the server, a GTID of the format :

server_uuid:transaction_id is written into the master's binary log.

This offers the following advantages:

  • Very helpful to set up a slave and create a replication setup.

  • User need not worry about fetching the master's binlog filename and position in the “CHANGE MASTER TO” command which is used to synchronise the slave with the master.

  • Applying GTIDs on slaves ensures consistency – since GTIDs are unique, it cannot be applied more than once on the server.

For a gtid enabled server, the following properties need to be set on both Master and Slave configuration files as shown below in Master.cnf and Slave.cnf

gtid-mode=on

enforce-gtid-consistency=true

log-bin

log-slave-updates=true

Here are the steps to achieve this:

Have a configuration file for master and slave with the below mentioned properties.

So the configuration file for a Master and Slave looks like:

Master.cnf

[mysqld]

port=3306

socket=/tmp/mysql3306.sock

binlog-format=MIXED

log-bin

log-slave-updates=true

gtid-mode=on

enforce-gtid-consistency=true

master-info-repository=TABLE

relay-log-info-repository=TABLE

sync-master-info=1

binlog-checksum=CRC32

master-verify-checksum=1

server-id=1

report-host=localhost

datadir=/export/gtid-test/master-data

innodb-file-per-table=on 

Slave.cnf

[mysqld] 

port=3307

socket=/tmp/mysql3307.sock 

binlog-format=MIXED 

log-bin

log-slave-updates=true 

gtid-mode=on 

enforce-gtid-consistency=true 

master-info-repository=TABLE 

relay-log-info-repository=TABLE 

slave-parallel-workers=2

binlog-checksum=CRC32 

slave-sql-verify-checksum=1

server-id=2

binlog-rows-query-log_events=1

datadir=/export/gtid-test/slave-data 

report-host=localhost

On the Master:

Start the server with this configuration file:

./mysqld –defaults-file=/export/gtid-test/master.cnf &

Create a user and grant 'replication' privileges to that user:

mysql> create user 'replication'@'localhost' identified by 'reppwd';

mysql> grant super,replication slave on *.* to 'replication'@'localhost';

Now, you can use Mysql Enterprise Backup(MEB), which will simplify this task of setting up a new slave from an existing server (which will serve as “master” in this replication environment),

On MEB:

1. Use Mysql Enterprise Backup to take a backup of the master.

./mysqlbackup -uroot --socket=/tmp/mysql3306.sock –backup-dir=/export/gtid-test/slave-data-to-rest/ backup

Now the meta folder under the backup directory contains a new file named backup_gtid_executed.sql.

(In this case, /export/gtid-test/slave-data-to-rest/meta/backup_gtid_executed.sql)

Here are the contents of backup_gtid_executed.sql:

# On a new slave, issue the following command if GTIDs are enabled:

SET @@GLOBAL.GTID_PURGED='6efe48e8-b63c-11e3-a730-0021cc6bab7c:1-12';

# Use the following command if you want to use the GTID handshake protocol:

# CHANGE MASTER TO MASTER_AUTO_POSITION=1;

MEB will simplify the task of cloning a slave with the help of this file which contains the sql to set the GTID_PURGED on the slave (this is the GTID_EXECUTED value of the Master)

On the Slave:

2. Now to setup a new slave server, restore the backed up contents using “copy-back-and-apply-log” operation:

./mysqlbackup --defaults-file=/export/gtid-test/slave.cnf --backup-dir=/export/gtid-test/slave-data-to-rest/ copy-back-and-apply-log

slave.cnf contains the “datadir” where the backup contents will be restored. So no need to pass 'datadir' in the command line.

An image backup is much more efficient, as the image can be streamed onto the slave machine and restored directly. You can check out Restore directly on the remote Machine from backup stream for more information.

The new server is ready. Start the slave server.

./mysqld –defaults-file=/export/gtid-test/slave.cnf &

Observe that the restored directory is the datadirectory (as mentioned in slave.cnf) of the slave server

This can be synchronised with the master by doing the following simple steps:

mysql> show slave status;

This is an empty set as the slave is not synchronised still.

mysql> show global variables like '%gtid_executed%';

+---------------+------------------------------------------+

| Variable_name | Value |

+---------------+------------------------------------------+

| gtid_executed | 16446ee3-bad6-11e3-8530-0021cc6bab7c:1-2 |

+---------------+------------------------------------------+

1 row in set (0.00 sec)

3. Now to synchronise with Master – to set the gtid_purged, the gtid_executed on the slave need to be empty. Reset Master to do this.

mysql> reset master;

mysql> show global variables like '%gtid_executed%';

+---------------+-------+

| Variable_name | Value |

+---------------+-------+

| gtid_executed |     |

+---------------+-------+

4 a. Execute the backup_gtid_executed.sql to set the GTID_PURGED on the slave.

mysql> \. /export/gtid-test/slave-data-to-rest/meta/backup_gtid_executed.sql

4 b. Synchronise slave with Master;

mysql> change master to master_host='<hostname>', master_port=<port_number> master_auto_position=1;

Setting master_auto_position=1 will automatically replicate the changes.

5. Start the slave with the username and password to connect to Master.

mysql> start slave USER='replication' PASSWORD='reppwd';

mysql> show slave status \G

Look for:

Retrieved_Gtid_Set: 6efe48e8-b63c-11e3-a730-0021cc6bab7c:13

Executed_Gtid_Set: 6efe48e8-b63c-11e3-a730-0021cc6bab7c:1-13

which shows that the slave has all the transactions from 1-13.

This way, the backup taken with Mysql Enterprise Backup can be used to set any number of slaves for the master in a replication environment.

You can also refer : Using MEB with Replication

Thursday Apr 03, 2014

Data Encryption with MySQL Enterprise Backup 3.10

Introduction

MySQL Enterprise Backup (MEB) 3.10 introduces support for encrypted backups by allowing backup images, or single-file backups, to be encrypted. However, backups stored in multiple files in a backup directory can not be encrypted.

Any MEB command that produces a backup image can be optionally requested to encrypt it. The encrypted backup image can be stored in a file or tape in the same way as an unencrypted backup image. Similarly, any MEB command that reads data from a backup image accepts also an encrypted backup image. This means that encrypted backups can be used in all the same situations as unencrypted backup images.

MEB encrypts data with Advanced Encryption Standard (AES) algorithm in CBC mode with 256-bit keys. AES is a symmetric block cipher which means that the same key is used both for encryption and decryption. The AES cipher has been adopted by the U.S. government and it is now used worldwide.

A new format for the encrypted backup image is introduced. This is a proprietary format developed by Oracle and it allows efficient encryption and decryption in parallel.

Encryption keys

Encryption keys are strings of 256 bits (or 32 bytes) that are represented by strings of 64 hexadecimal digits. The simplest way to create an encryption key for MEB is to type 64 randomly chosen hexadecimal digits and save them in a file. Another method is to use some shell tool to generate a string of random bytes and encode it as hexadecimal digits. For example, one could use the OpenSSL shell command to generate a key as follows:

$ openssl rand 32 -hex
8f3ca9b850ec6366f4a54feba99f2dc42fa79577158911fe8cd641ffff1e63d6

This command uses random data generated on the host for creating the key. Whichever method is used for the creation of the key, the essential point is that the resulting key consists of random bits.

The security of MEB encryption is based on two rules that apply not only to MEB but to all encryption schemes using symmetric block ciphers:

Rule 1: The encryption keys must be random.

Rule 2: The encryption keys must remain secret at all times.

When these rules are followed, it is very difficult for unauthorized persons to get access to the secure data.

Encryption keys can be specified either on the command-line with the

--key=KEY 
option where KEY is a string of 64 hexadecimal digits, or in a file with the
--key-file=FILENAME

option where FILENAME is the name of the file that contains a string of 64 hexadecimal digits.

It is important to notice that specifying the key on the command-line with the --key option is generally not secure because the command-line is usually visible to other users on the system and it may even be saved in system log files that may be accessible by unauthorized persons. Therefore, the --key-file option should be preferred over the --key option in all production environments, and the use of the --key option should be limited to testing and software development environments.

Using encryption

Encryption is very simple to use. Any MEB command that produces a backup image can be requested to encrypt it by specifying the --encrypt option with either --key or --key-file option. The following example shows how to make a compressed backup and store it as an encrypted backup image.


$ mysqlbackup --encrypt --key-file=/backups/key --compress --backup-dir=/full-backup  --backup-image=/backups/image.enc  backup-to-image

MySQL Enterprise Backup version 3.10.0 Linux-3.2.0-58-generic-i686 [2014/03/04]

Copyright (c) 2003, 2014, Oracle and/or its affiliates. All Rights Reserved.

 mysqlbackup: INFO: Starting with following command line ...

 /home/pekka/bzr/meb-3.10/src/build/mysqlbackup --encrypt

        --key-file=/backups/key --compress --backup-dir=/full-backup

        --backup-image=/backups/image.enc backup-to-image

 mysqlbackup: INFO:

IMPORTANT: Please check that mysqlbackup run completes successfully.

           At the end of a successful 'backup-to-image' run mysqlbackup

           prints "mysqlbackup completed OK!".

140306 21:40:33 mysqlbackup: INFO: MEB logfile created at /full-backup/meta/MEB_2014-03-06.21-40-33_compress_img_backup.log

 mysqlbackup: WARNING: innodb_checksum_algorithm could not be obtained from config or server variable and so mysqlbackup uses the default checksum algorithm 'innodb'.

--------------------------------------------------------------------

                       Server Repository Options:

--------------------------------------------------------------------

...

...

...

Backup Image Path = /backups/image.enc

 mysqlbackup: INFO: Unique generated backup id for this is 13941348344547471

 mysqlbackup: INFO: Uses LZ4 r109 for data compression.

 mysqlbackup: INFO: Creating 18 buffers each of size 16794070.

140306 21:40:36 mysqlbackup: INFO: Compress Image Backup operation starts with following threads

        1 read-threads    6 process-threads    1 write-threads

140306 21:40:36 mysqlbackup: INFO: System tablespace file format is Barracuda.

140306 21:40:36 mysqlbackup: INFO: Starting to copy all innodb files...

 mysqlbackup: INFO: Copying meta file /full-backup/backup-my.cnf.

 mysqlbackup: INFO: Copying meta file /full-backup/meta/backup_create.xml.

140306 21:40:36 mysqlbackup: INFO: Copying /sqldata/simple-5.6/ibdata1 (Barracuda file format).

140306 21:40:36 mysqlbackup: INFO: Found checkpoint at lsn 188642964.

...

...

...

140306 21:40:51 mysqlbackup: INFO: Compress Image Backup operation completed successfully.

 mysqlbackup: INFO: Image Path = /backups/image.enc

-------------------------------------------------------------

   Parameters Summary         

-------------------------------------------------------------

   Start LSN                  : 188642816

   End LSN                    : 188642964

-------------------------------------------------------------

mysqlbackup completed OK! with 2 warnings



This resulting encrypted backup image (file "image.enc") can be used with all commands that accept a backup image in the same way as an unencrypted backup image. For example, one could restore the server from the encrypted backup as follows:


$ mysqlbackup --decrypt --key-file=/backups/key --uncompress --backup-image=/backups/image.enc --backup-dir=/full-backup copy-back-and-apply-log

MySQL Enterprise Backup version 3.10.0 Linux-3.2.0-58-generic-i686 [2014/03/04]

Copyright (c) 2003, 2014, Oracle and/or its affiliates. All Rights Reserved.

 mysqlbackup: INFO: Starting with following command line ...

 /home/pekka/bzr/meb-3.10/src/build/mysqlbackup --decrypt

        --key-file=/backups/key --uncompress --backup-image=/backups/image.enc

        --backup-dir=/full-backup copy-back-and-apply-log

 mysqlbackup: INFO:

IMPORTANT: Please check that mysqlbackup run completes successfully.

           At the end of a successful 'copy-back-and-apply-log' run mysqlbackup

           prints "mysqlbackup completed OK!".

 mysqlbackup: INFO: Backup Image MEB version string: 3.10.0 [2014/03/04]

 mysqlbackup: INFO: The input backup image contains compressed backup.

140310 12:51:54 mysqlbackup: INFO: MEB logfile created at /full-backup/meta/MEB_2014-03-10.12-51-54_copy_back_cmprs_img_to_datadir.log

...

...

140310 12:52:14 mysqlbackup: INFO: We were able to parse ibbackup_logfile up to

          lsn 188642964.

140310 12:52:14 mysqlbackup: INFO: The first data file is '/home/pekka/sqldata/copyback-simple-5.6/ibdata1'

          and the new created log files are at '/home/pekka/sqldata/copyback-simple-5.6'

140310 12:52:14 mysqlbackup: INFO: Apply-log operation completed successfully.

140310 12:52:14 mysqlbackup: INFO: Full Backup has been restored successfully.

mysqlbackup completed OK!



In these examples we have used the --key-file option for specifying the encryption key because it is more secure than giving the key on the command-line with the --key option.

Tips

This section describes two tips that may be useful when working with encrypted backups.

The "Wrong key" error

Encryption and decryption use the same key. If decryption is attempted with a key different from the encryption key, a wrong key error occurs. When this happens, MEB prints an error message like the one shown below.


MySQL Enterprise Backup version 3.10.0 Linux-3.2.0-58-generic-i686 [2014/03/04]

Copyright (c) 2003, 2014, Oracle and/or its affiliates. All Rights Reserved.

 mysqlbackup: INFO: Starting with following command line ...

        mysqlbackup --backup-image=/backups/image.enc --decrypt

        --key-file=/key-file2 list-image

 mysqlbackup: INFO:

IMPORTANT: Please check that mysqlbackup run completes successfully.

           At the end of a successful 'list-image' run mysqlbackup

           prints "mysqlbackup completed OK!".

 mysqlbackup: INFO: Creating 14 buffers each of size 16777216.

 mysqlbackup: ERROR: Failed to decrypt encrypted data in file /backups/image.enc : the file may be corrupted or a wrong encryption key was specified.



For the user, this can be problematic because two possible reasons for the failure are offered in the error message: either the backup is corrupted or a wrong key was supplied. This is not a bug or feature of MySQL Enterprise Backup but, instead, it is a theoretical limitation imposed by the encryption scheme. It is not possible even in theory to distinguish with absolute certainty between these two explanations when decryption fails.

However, these two explanations are not always equally likely. If decryption fails at the very start without decrypting any data, then it is more likely that a wrong key was supplied. On the other hand, if the decryption fails later after some data was successfully decrypted, then it is very likely that the correct key was given but the encrypted backup is broken. Using these two rules it is possible to determine with high probability the cases where decryption fails because of a wrong key.

Recognizing encrypted backups

On Unix-like operating systems "magic numbers" may be used for identifying the type of a file. Magic numbers are patterns in files that allow recognizing the type of a file by examining the first bytes in the file. Both the unencrypted backup images and encrypted backup images have magic numbers that can be used by shell tools to detect the file type. For example, by putting these lines to the /etc/magic file

0   string  MBackuP\n   MySQL Enterprise Backup backup image
0   string  MebEncR\n   MySQL Enterprise Backup encrypted backup


the file command detects the backups images as follows:

$ file /backups/image1 /backups/image2
/backups/image1: MySQL Enterprise Backup backup image
/backups/image2: MySQL Enterprise Backup encrypted backup


Monday Nov 25, 2013

MEB integration with Workbench

This blog talks about MySQL Enterprise Backup integration with Workbench and how the Workbench UI can be used to configure and operate MEB.[Read More]

Sunday Sep 29, 2013

Backing up full server instance using MySQL Enterprise Backup

Introduction:

MySQL Enterprise Backup(MEB) takes fast, consistent backups of MySQL server data, and helps in restoring the server to source server's data at the time of backup. But most of the times it is as much important to have same source server's state(server configuration like server global variables, plugins), as data. As backups become more frequent, server variables modified, plugins added or removed, it is very difficult to keep track of this changing server states for every backup. MEB 3.9.0 helps user in providing a complete backup so that the restored server can run with exactly the same state as that of the source server at the time of the backup.

MEB 3.9.0 performs full server instance backup,  which, on top of the log files and data files, also includes all the global variables and plugins(both internal and external) details. With this feature, backup-content.xml, a meta file under "meta" folder of the backup directory , now additionally contains all the plugins details like name, status, type etc under <plugins> section. In addition, there are two new files created under backup directory

  • server-my.cnf - contains all the global variables with non-default values for that server environment(MySQL server version, Operating System, Hardware Architecture etc).
  • server-all.cnf - contains all the global variables, that includes all the variables with non-default values and the other global variables with default values.

Advantages of Full Server Instance Backup:

  • Create replica - User can clone source server state by using either server-my.cnf or server-all.cnf file in the backup as defaults-file for starting the target server. As most of the global variables default value depend on the server environment, user can create a server with same state even if the target environment is different from source by using server-all.cnf as defaults file. If the target environment is same as source, user can use either of the files.
  • Keep a history of global variables - This new feature reduces the user's task for storing the state of the server, if changed, before every backup or incremental backup, so user need not worry about keeping track of server global variables. With this feature, now we can figure out non-default values of global variables for the running server with server-my.cnf.
  • Full plugins information - With all the plugins information backed up, this information will be used while installing missing plugins on restored server. Plugin details like type, status, library can be used to install missing plugins with the same configuration of the source.

Using Full Server Instance Backup:

Backup:

From MEB 3.9 onwards, this feature is enabled by default for all kinds of backup(i.e normal, incremental, image, compressed etc). That is there is no need to turn on any feature or use any option and all backups are full server instance backups.

Note: Binary logs and *info files used for replication and Innodb buffer pool details, which are also part of server instance, are not included in backups. Server plugins details are copied, but actual plugins binaries are not copied.

Restore:

After copy-back operation, server-all.cnf, server-my.cnf will be present in restored data directory. If there were any external plugins exist in source server, copy-back operation throws a warning about the missing plugins to install.

Starting Server:

The files server-my.cnf, server-all.cnf, which could be used as defaults-file to start the server on the restored data directory. When source and target environments are same, restoring server using server-my.cnf will be easier than using server-all.cnf as server-my.cnf has fewer global variables to verify or modify.

Note: User has to be careful while starting another server instance on the same host using server-my.cnf, server-all.cnf files without changes. There is a possibility of modifying source server settings or data, as some file paths like innodb_log_group_home_dir, innodb_log_group_home_dir,tmpdir,general-log etc are related to source server.

Incremental Backup:

The files server-my.cnf,server-all.cnf reflect the state of the server at the time of a incremental backup and it is desirable to have the same state after applying the incremental backup. So after apply-incremental-backup operation, full backup's server-my.cnf and server-all.cnf will be overwritten by corresponding incremental backup's server-my.cnf and server-all.cnf files.

Thursday Sep 19, 2013

Backing up selective innodb tables using MEB.

MySQL 5.6 introduced the TTS(transportable table spaces) feature which enables moving a table from one server to another. This feature coupled with MEB 3.9 enables backing up a set of tables matching (regex specified with) the –include option.

The backup of selective tables using transportable tablespaces feature of innodb is referred as tts/selective backup in the remainder of the section.

The difference between a regular partial backup and with using tts is that the regular partial backups are stand alone and cannot be plugged into a another server where as the tts backups in contrast enables the tables to be plugged into another server instance


The Selective Backup Operation

To specify a set of tables to be backed up use the --use-tts option along with the --include=[regex] option for the backup operation. --use-tts option supports two values with-minimum-locking and with-full-locking.

with-minimum-locking -  This is the default option. The tables being backed up are hot copied in parallel along with the redo log. After the data file copy, the tables are locked in read only mode, the delta of the log is copied into the backup, and the locks are released. The advantage of this option is that the tables are available for modifications during most part of the back up process and are available in read only mode for a short duration.

with-full-locking - With this options the tables are locked in read only mode during the entire duration of the backup. As there cannot be any modifications while the backup is happening, the tables are consistent and the redo log is not backed up. This saves space and makes the apply log step faster as it just involves some book keeping operations.

Eg:
mysqlbackup --port=3306 --protocol=tcp --user=root –backup-dir=backupdir –include=Sales.Sales_*  --use-tts backup-and-apply-log


The Restore(copy-back) Operation

Restoring from a tts backup requires the server to be running in case of a tts backup unlike the other types of backup. The connection options of the server where the set of tables have to be restored need to be provided for the copyback of a tts backup.

Eg:
mysqlbackup --defaults-file=/backup-my.cnf --port=3406 --protocol=tcp --user=root --backup-dir=backupdir --datadir=<target_server_datadir> copy-back


Advantages of using MEB for tts Backup

Have a backup strategy for backing a subset of tables(for eg: backing up only important/most used tables).
Take advantage of compressed and image backup options supported by MEB.
This feature can effectively be used to copy a set of innodb tables from one server instance to another.  

This feature handles only tables having their own tablespaces(innodb_file_per_table on) and does not support partitioned tables.

Wednesday Jun 26, 2013

MySQL Enterprise Backup 3.8.2 has been released!

MySQL Enterprise Backup v3.8.2, a maintenance release of online MySQL backup tool, is now available for download from My Oracle Support  (MOS) website as our latest GA release.  It will also be available via the Oracle Software Delivery Cloud in approximately 1-2 weeks. A brief summary of the changes in MySQL Enterprise Backup version 3.8.2 is given below.


  A. Functionality Added or Changed: 

  • MySQL Enterprise Backup has a new --on-disk-full command line option. mysqlbackup could hang when the disk became full, rather than detecting the low space condition. mysqlbackup now monitors disk space when running backup commands, and users can now specify the action to take at a disk-full condition with the --on-disk-full option. For more details, refer this page
  • MySQL Enterprise Backup has a new progress report feature, which periodically outputs short progress indicators on its  operations to user-selected destinations (for example, stdout, stderr, a file, or other choices). For more details on progress report options, refer here

  B. Bugs Fixed:

  • When --innodb-file-per-table=ON, if a table was renamed and backup-to-image was in progress, apply-log would fail when being run on the backup. (Bug #16903973) 
  •  MySQL Server failed to start after a backup was restored if  there had been online DDL transactions on partitioned tables during the time of backup. (Bug #16924499) 
  • apply-incremental-backup might fail with an assertion error if  the InnoDB tables being backed up were created in Barracuda format and with their KEY_BLOCK_SIZE  values  different from the innodb_page_size . This fix ensures that different KEY_BLOCK_SIZE  values are handled properly during incremental backup and apply-incremental-backup operations. 
  • If a table was renamed following a full backup, a subsequent incremental backup could copy the .frm file with the new name, but not the associated .ibd file with the new name. After a  restore, the InnoDB data dictionary could be in an  inconsistent state. This issue primarily occurred if the table  was not changed between the full backup and the subsequent  incremental backup. Bug #16262690)
  •  After a full backup, if a table was renamed and modified,  apply-incremental-backup would crash when run on the backup directory. (Bug #16262609)
  • The value of the binary log position in backup_variables.txt  could be different from the output displayed during the   backup-and-apply-log operation. (This issue did not occur if  the backup and apply-log steps were done separately.) (Bug  #16195529)
  • When using the --only-innodb-with-frm option, MySQL Enterprise Backup tried to create temporary files at unintended locations in the file system, which might cause a failure when, for example, the user had no write privilege for those locations.   This fix makes sure the paths for the temporary files are  correct. (Bug #14787324)
  •  A backup process might hang when it ran into an LSN mismatch between a data file  and the redo log. This fix makes sure the process does not hang and it displays an error message showing the  name of the problematic data file (Bug #14791645)

Please post your questions / comments about Backup in forums.

Thanks,

MEB Team


Friday Feb 08, 2013

Truly Parallel backup (MySQL Enterprise Backup 3.8 and later)

How do you implement a parallel algorithm for a software which needs to be streamed to tapes?
How do you ensure that you have the capability to be able to tune the level of parallelism for varying input and output devices and varying levels of load?
These were some of the questions that we needed to answer when we were trying to implement multi-threading capability for MySQL Enterprise Backup (MEB).
The trivial way of achieving parallelism is by having the multiple threads pick up the different files (in a file per table) scenario. But this did not seem adequate because:
a) The sizes of these files (corresponding to the tables) could be different and then one large file would limit the level of parallelism since it would be processed by a single thread.
b) If you have to stream the backup how do you reconcile these multiple files being streamed by separate threads? Large backups are streamed directly to tape so it is better to have a single file being output and not multiple files.
c) If you buffer each file and wait for a file to be completely processed and then push it to tape then it is not true streaming because you are using intermediate disk space to save the incomplete portions of all the files.
The answer that we found was to implement the parallel algorithm using a horizontal strategy instead of a vertical strategy.


In the vertical strategy, each thread acts on a separate file. This limits streaming since the file sizes can vary.
In the horizontal strategy, each file is broken into a sections (denoted by multiple colors). A separate thread is assigned to operate on a single section.
Parallel operations are then possible for reading , processing and writing of these file subsections because no two threads will be operating on the same section of the file.
This setup is especially useful when using compression since there can be multiple threads performing compression while the read and write continues in parallel.
There may be additional overhead of ensuring that the buffers are in the correct order when they are written out, but since most of the buffers of the same size and having similar operations being performed, the overhead is minimal.
You get truly serialized output that is streamed to tape as it gets processed. If you are streaming to a remote host or to tape, there is almost no additional space required on your main server. We call this new mechanism parallel backup because we are achieving parallelism thereby making the backup faster. Indeed, using parallel backup may see up to 10 times the speed of a normal backup in certain scenarios.
The graph below shows the time it took for backup for MEB 3.7.1 v/s MEB 3.8 using varying number of threads.



Note : This is a 16 GB, 2 x 2000 MHz, 2 RAID DISKS (1027 GB,733.9GB) machine running Oracle Linux.

As you can see above; MEB 3.8 provides options to configure the number of threads you use for reading, writing and processing. Lets denote RT, PT and WT as number of Read, Process and Write threads respectively. Default values for MEB 3.8 is RT=3,PT=3, WT=3 which is changing in MEB 3.8.1 to RT=1, PT=6, WT=1.

This is close to the fastest backup we get in the graph above. The reason for not choosing RT=1, PT=12, WT=1 (which is the fastest) is because the CPU gets very highly utilized in the 1,12,1 configuration.

Remember, the read write throughput depends on your input and output devices. It is possible that multiple threads do not give you a better performance for read or write v/s a single thread.

There are also options available to have a configurable number of buffers used by these threads.

Each buffer is of size 16MB. You should have at-least [RT+PT+WT+ (MAX(RT,PT,WT) ] number of buffers so that you get optimal parallelism.

For Example if RT=1, PT=6, WT=1 then you should configure 1+6+1+6 = 14 buffers (default in MEB 3.8.1)

If for example you configure multiple threads but configure only 1 buffer then your backup is not taking advantage of parallelism at all. The read thread reads into the single buffer, buffer is then processed, written and then freed. The read thread is waiting for a buffer to be free to read into it; so it is like a serial process.

One more thing to note is that the number of buffers is limited by the memory limit configured for backup (default 300MB). Please ensure that you configure enough memory to be able to distribute it to the buffers you have configured. If the memory limit configured is less then what is required for the configured number of buffers; MEB will automatically decrease the number of buffers to fit into the memory limit. Based on the default values, if you are configuring more than 18 buffers you will need to increase the memory limit.

Please look at the previous 3.8 blog for detailed configuration examples :

https://blogs.oracle.com/mysqlenterprisebackup/entry/parallel_backup_in_mysql_enterprise

or into our documentation of this feature at

http://dev.mysql.com/doc/mysql-enterprise-backup/3.8/en/backup-capacity-options.html

Cheers 

and remember the wise DBA advise:

If you don't verify your backups periodically it is like not having backups at all


Thursday Feb 07, 2013

MySQL Enterprise Backup 3.8.1 release for 5.6 Server

The MySQL Enterprise Backup 3.8.1 release's main goal was support MySQL 5.6 server. But also beyond that primary goal MEB team added some valuable new options and features to ensure you'll get most from the new features in 5.6 as well. At a glance, here are some of the highlights,

MEB copy of InnoDB undo log tablespaces

MySQL 5.6 introduces a new feature to store undo logs in separate files called as undo tablespaces for improved performance. These undo tablespaces are logically part of system  tablespace. All the commands associated with MEB - "backup", "apply-log" and "copy-back"  now take care of the undo tablespaces in the same way as they process the system tablespace. MEB now supports innodb_undo_directory[logs][tablespace] option variables. When backup is executed, undo datafiles (up to number specified by innodb_undo_tablespaces) are stored in same directory as the datafiles of system tablespace. During copy-back, files can be stored in a location specified by the user using option --innodb-undo-directory.

MEB support for Global transaction ID's

GTID feature is newly introduced in MySQL 5.6 server. GTID's help to track the data being replicated particularly with the automatic slave promotion when a master fails.
When server is started with GTID's enabled and backup is performed on the master server, mysqlbackup produces a new file called as gtid_executed.sql in meta backup directory . This file is used after restoring the backup data on slave server and contains GTID_PURGED option. This provides information from the server at the end of the backup, thereby ensuring that replication starts from the point in time when backup was taken.

UNC Path name support

MEB now supports UNC path names by specifying a location of network resource such as shared file, directory or printer. This feature helps to start backups using windows task scheduler when shared drives cannot be mapped to a drive letter. Support for UNC path names also allows MEB to take backups when user is not logged in.
eg: ./mysqlbackup --defaults-file=/home/my/my.cnf  --backup-dir="\\mysql\\testmeb\" backup

Where testmeb is shared network directory on windows.

When the shared name is corrupt / invalid, MEB detects and then tries to access the files pointed to by the path and prints an error message.

MEB support for different page size settings for InnoDB

InnoDB page size is the server parameter that is associated with all the innodb tablespaces in the MySQL instance. By default the value of this size used to be 16K in the versions less than MySQL 5.6. But from MySQL 5.6, this option is made user configurable to 4k, 8k, 16k etc. Starting from MEB 3.8.1, Backup will work successfully when server is started with different innodb_page_size values. The innodb-page-size option can also be specified in the mysqlbackup command line but MEB will ignore the option provided the connection to server is available. If innodb_page_size option is not specified in command line or if connection to server is not available, then the value of innodb-page-size is read from the header of the innodb data files.

 InnoDB Checksum Algorithm Support

MEB 3.8.1 introduces new option support of --innodb-checksum-algorithm in MySQL 5.6. This option can also be specified on the command line. A default option is used if its not  specified in the command line and also if the connection to the server is offline. Without the support for this new option, MEB could not start the server after sequence of backup, apply-log and restore operations. One thing to be noted here is,
a. Server backed with strict_crc32, strict_innodb or strict_none checksum algorithms should be restored with the same algorithm
b. Server backed with mixed algorithms should not be restored to a server with strict_* algorithms.

Backup of system tablespace with fractional megabyte.

It sometimes happens that InnoDB engine extends datafiles of system tablespace by few megabytes. But if the disk is full, then system tablespace will actually extend to  fractional megabytes. During such cases, MEB performs a consistency check on the sizes of InnoDB datafiles and if the size does not match the size of the file on the disk, a warning is reported.That is MEB does not backup the fractional datafile in the system tablespace.

Backup restore file per table tablespaces at different locations.

In MySQL 5.6, it is possible to create new InnoDB table with per-table tablespace outside of data directory where .ibd file should be created instead of default location in the database sub directory. For each .ibd file, a .isl file is created in the database subdirectory containing absolute path name acting like a symbolic link to actual tablespace file. All the MEB operations are now able to read the .isl files to locate the .ibd files during backup. During backup, both .isl and .ibd files are copied to the backup directory but .isl is renamed as .bl file. During copy-back, .ibd files are being copied to a location specified in .bl file. But if the target location is changed where the restore of the backup should be performed, then one needs to manually edit the .bl file before doing the restore and specify the abs path name where .ibd files should go.

The above mentioned are new features added to backup code but this release also includes various bug fixes, please take a look at the MEB 3.8.1 reference manuals for more details.

The MEB team has put great deal of efforts to ensure that latest release of MEB 3.8.1 is compliant with MySQL 5.6 server. Please try this new MEB 3.8.1 version with MySQL 5.6 server and as always send us your feedback / comments here. MEB 3.8.1 is now available in My Oracle Support site and will very soon be available in Oracle's Cloud delivery site.

Once again, I would like to thank entire MEB team to deliver this release on time and with many valuable new additions.


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