Logging is a very important
diagnostic tool for understanding the behavior of the application as well as
troubleshooting any issue with the application. Since MySQL Enterprise Backup
(MEB) is a command line application, there is little interaction with the
myriad of operations going on behind the scenes. Thus, logging messages are very
important for knowing the progress of current operation as well as learning
more about errors should they occur. The messages logged by MEB are written to
the console and the log file as depicted in the following diagram, which looks
similar to the Tee command in UNIX.
By default, MEB creates the log file in the default ‘<backup_dir>/meta’
directory with a name like MEB_<Date.time>_<operation_name>.log. For example – MEB created a log
file with the name, ‘MEB_2017-02-24.07-47-09_backup.log’, for the backup
operation executed to save the log messages. User may specify any other existing directory
to create the log file using the --messages-logdir= <directory_ path>
option. Users may also skip the log file creation using the --skip-messages-logdir
option, but it is not recommended.
Prior to 4.1 release, the log messages are printed as shown
Notice how the messages seem to
interlace, making it harder to read a logical flow from the output. There were
several reasons for this.
The trace levels of the
log messages, in the order of increasing fineness, are:
Logging has been greatly improved In the 4.1
release. They are now printed as shown below.
The improvements are small but
have a profound effect on readability and usability. These improvements include
|Thread Name||Thread Description|
|RDR1||ReaDeR thread #1|
|PCR1||ProCessoR thread #1|
|WTR1||WriTeR thread #1|
|CLD1||CLouD thread #1|
|RLR1||Redo Log Reader thread #1|
|RLP1||Redo Log Processor thread #1|
|RLW1||Redo Log Writer thread #1|
|ALW1||Apply Log Worker thread #1|
hope these small improvements will be useful for troubleshooting purpose. Try
out the latest version and provide us feedback on how we can improve it
further. For more details and usage samples, please refer MySQL Enterprise
Backup 4.1 User’s Guide .