Friday Jan 22, 2010

Comparative data of ORACLE 10g on SPARC & SOLARIS 10

Oracle 10g OLTP performance on SPARC chips

A boring ratio

Customers would love to have their performance levels linked to their hardware. But more often than you think, they migrate from System X (designed 10 years ago) to System Y (fresh from the oven) and are surprised with the performance improvements. In the past two years, we have completed many successful migrations from F15k/E25k servers to new Enterprise Servers M9000. Customer have reported great improvements in throughput and response time. But what can you really expect and what percentage of the improvement is actually due to the operating system enhancement ? Can the recent small frequency increase on our SPARC64 VII chipset be at all interesting ? The new SPARC64 VII 2.88Ghz available on our M8000 and M9000 flagships propose no architectural change, no additional features and a modest frequency increase going from 2.52 Ghz to 2.88 Ghz - for a ratio of 1.14. We could stop our analysis there and label this change 'marginal' or 'not interesting'. But my initial testings showed a comparative OLTP peak throughput to be way higher than this frequency-based ratio.

What happened ?

A passion for Solaris

Most of the long term Sun employees have a passion for Solaris. Solaris is the uncontested Unix leader and include such a huge amount of features that when you are a Solaris addict, it is difficult to get in love with another Operating System. And Oracle executives made no mistake : Sun has the best UNIX kernel & performance engineers in the world. Without them, Solaris would not scale today to a 512 hardware thread system (M9000-64).

But of course, Solaris is a moving target. Every release brings its truck load of features, bug fixes and other performance improvements. Here are critical fixes done between Solaris 10 Update 4 and the brand new Solaris 10 Update 8 influencing Oracle performance on the M9000 :

  • In Solaris 10 Update 5 (05/08), we optimized interrupt management ( cr=5017144), math operations (cr=6491717). We also streamlined CPU yield (cr=6495392) and cache hierarchy (cr=6495401).

  • In Solaris 10 Update 6 (10/08), we optimized libraries and implemented shared context for Jupiter (cr=6655597 & 6642758)

  • In Solaris 10 Update 7 (05/09), we enhanced MPXIO as well as the PCI framework (cr=6449810 and others) and improved thread scheduling (cr=6647538). We also enhanced Mutex operations (cr=6719447).

  • Finally, in Solaris 10 Update 8 , after long customer escalations, we fixed the single threaded nature of callout processing (cr=6565503-6311743). [This is critical for all calls made to nanosleep & usleep.] We also improved the throughput & latency of the very common e1000g driver (cr=6335837 + 5 more) and optimized the mpt driver (cr=6784459). We cleaned up interrupt management (cr=6799018) and optimized bcopy and kcopy operations (cr=6292199). Finally, we improved some single threaded operations (cr=6755069).

My initial SPARC64 VII iGenOLTP tests were done with Solaris 10 Update 4. But I could not test the new SPARC64 VII 2.88Ghz with this release because it was not supported ! Therefore, I had to compare the new chip performance to SPARC64VII 2.52Ghz using each S10U4 and S10U8. We will see below that most of the improvements are not coming from the frequency increase but from Solaris itself.

Chips & Chassis

Please find below , the key characteristics of the chips we have tested :











Die size

356 sq mm

421 sq mm

421 sq mm

421 sq mm


295 million

540 million

600 million

600 million











Total threads






1.5 Ghz

2.28 Ghz



L1 I-cache

64 KB

128 KB/core

512 KB

512 KB

L1 D-cache

64 KB

128 KB/core

512 KB

512 KB

On-chip L2

2 MB

6 MB

6 MB

6 MB

Off-chip L3

32 MB




Max Watts

56 W

120 W

135 W

140 W


28 W

30 W

17 W

17 W

Note on (+): The new SPARC64 VII is not officially labeled with a plus sign in order to reflect the absence of new features.

Now, here is our hardware list. Note that to avoid the need for a huge Client system, we ran this iGenOltp workload in a Console/Server mode. It means that the Java processes sending SQL queries via JDBC are running directly on the server tested. While this model was unusual ten years ago in the era of Client/Server, it is more and more commonly found today in new customer deployments.











# chips





Total hardware threads






1.5 Ghz

2.28 Ghz

2.52 Ghz

2.88 Ghz

System Clock

150 Mhz

960 Mhz

960 Mhz

960 Mhz~


64 GB

64 GB

64 GB\*

64 GB\*

Operating System

Solaris 10 Update 4

Solaris 10 Update 4

Solaris 10 Update 4 & 8

Solaris 10 Update 8

Console system





64 GB cache

Opteron quad-core

25 TB


200 Hitachi HDD

15k RPM


Note on (~): While the system clock has not changed, the new M9000 CMUs are equipped with an optimized Memory Access Controller labeled MAC+. The MAC+ chip set is critical for system reliability, in particular for the memory mirroring and memory patrolling features. We have not identified performance improvements linked to this new feature.

Note on (\*): Those domains have 128GB total memory. To compare apple-to-apple, 64GB of memory are allocated, populated and locked in place with my very own _shmalloc tool.


The iGenOLTPv4 workload is a Java-based lightweight OLTP database workload. Simulating a classic Order Entry system, it is tested in stream mode (I.e no wait time between transactions). For this particular exercise, we have created a very large database of 8 Terabyte total. This database is stored on the SE9990V using Oracle ASM. We query 100 million customer identifiers on this very large database in order to create an I/O intensive (but not I/O bound) workload similar to the largest OLTP installations in the world. (Example : the E25ks running the bulk load of Oracle internal applications). The exact throughput in number of transactions per second and average response times are reported and coalesced for each scalability level. For this test, we used Solaris 10 Update 4 & 8, Java version 1.6 build 16, and the Oracle database server

Performance notes :

  • In peak, the new SPARC64VII 2.88Ghz produce 1.10x OLTP throughput compared to the 2.52Ghz on S10U8.

  • But compared to the 2.52Ghz chips on S10U4, the ratio is 1.54x and compared to the SPARC64 VI it is 2.38x.

  • For a customer willing to upgrade a E25k equipped with 1.5Ghz chips, the throughput ratio is 4.125 ! It means that we can easily replace a 8 boards E25k with a 2 boards M8000 for better throughput and improved response times.

  • Average transaction response times in peak are 126 ms on the UltraSPARC IV+ domain, 87ms on the SPARC64 VI, 82 ms on the SPARC64VII 2.52Ghz (U4), 77 ms on the SPARC64 VII 2.52Ghz (U8) and 72 ms on the latest chip.


As expected, Oracle OLTP improvements due to the new SPARC64VII chip are modest using the latest Solaris 10. However, all the customer already in production using previous release of Solaris 10 will see throughput improvement up to 1.54x. Most likely, this is enough to motivate a refresh of their system. And all E25k customers have now a very interesting value proposition with our M8000 and M9000 chassis.

See you next time in the wonderful world of benchmarking....

Tuesday Mar 17, 2009

Improving MySQL scalability blueprint

My previous blog entry on MySQL scalability on the T5440 is now completed by a Sun BluePrint that you can find here.

See you next time in the wonderful world of benchmarking....
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Monday Nov 10, 2008

Scaling MySQL on a 256-way T5440 server using Solaris ZFS and Java 1.7

Scaling MySQL on a 256-way T5440 server using Solaris ZFS and Java 1.7

A new era

In the past few years, I published many articles using Oracle as a database server. As a former Sybase system administrator and former Informix employee, it was obviously not a matter of personal choice. It was just because the large majority of Sun's customers running databases were also Oracle customers.

This summer, in our 26 Sun Solution Centers worldwide, I observed a shift. Yes, we were still seeing older solutions based on DB2, Oracle, Sybase or Informix being evaluated on new Sun hardware. But every customer project manager, every partner, every software engineer working on a new information system design asked us : Can we architect this solution with MySQL ?

In many cases, if you dared to reply YES to this question, the next interrogation would be about the scalability of the MySQL engine.

This is why I decided to write this article.


Please find below my initial goals :

  1. Reach a high throughput of SQL queries on a 256-way Sun SPARC Enterprise T5440

  2. Do it 21st century style i.e. with MySQL and ZFS , not 20th century style i.e with OraSybInf... and VxFS

  3. Do it with minimal tuning i.e as close as possible as out-of-the-box

This article is describing how I achieved this goals. It has two main parts : a short description of the technologies used, then a showing of the results obtained.

Sun SPARC Enterprise T5440 server
The T5440 server is the first quad-socket server proposing 256 hardware threads in just four rack units. Each socket host a UltraSPARC T2 Plus processor which propose eight cores and 64 simultaneous threads into a single piece of silicon. While a lot of customers are interested in the capacity of this system to be divided into 128 two-way domains, this article explores the database capacity of a single 256-way Solaris 10 domain.

The Zettabyte file system
Announced in 2004 and introduced part of OpenSolaris build 27 in November 2005, ZFS is the one-and-only 128-bit file system. It includes many innovative features like a copy-on-write transactional model, snapshots and clones, dynamic striping and variable block sizes. Since July 2006, ZFS is also a key part of the Solaris operating system . A key difference between UFS and ZFS is the usage of the ARC [Adaptive Replacement Cache] instead of the traditional virtual memory page cache. To obtain the performance level shown in this article, we only had to tune the size of the ARC cache and turn off atime management on the file systems to optimize ZIL I/O latency. The default ZFS recordsize is commonly changed for database workload. For this study, we kept the default value of 128k.

MySQL 5.1
The MySQL database server is the leading Open Source database for Web 2.0 environment. MySQL was introduced in May 1995 and has never stopped to be enriched with features. The 5.1 release is an important milestone as it introduces support for partitioning, event scheduling, XML functions and row based replication. While Sun is actively working on implementing a single instance highly scalable storage engine, this article is showing how one can reach a very high level of SQL query throughput using MySQL 5.1.29 64-bit on a 256-way server.

The SLAMD Distributed Load Generation Engine (SLAMD) is a Java-based application designed for stress testing and performance analysis of network-based applications. It was originally developed by Sun Microsystems, Inc., but it has been released as an open source application under the Sun Public License, which is an OSI-approved open source license. The main site for obtaining information about SLAMD is It is also available as a project.

iGenOLTP is a multi-processed and multi-threaded database benchmark. As a custom Java class for SLAMD, it is a lightweight workload composed of four select statements, one insert and one delete. It produces a 90% read/10% write workload simulating a global order system. For this exercise, we are using a maximum of 24 milllion customers and 240 million orders in the databases. The database is divided “sharded” in as many pieces as the number of MySQL instances on the system. [See this great article on database sharding]. For example, for 24 database instances, database 1 store customers 1 to 1 million, database 2 store customers 1 milion to 2 million and so on. The Java threads simulating the workload are aware of the database partitioning scheme and simulate the traffic accordingly.

This approach can be called “Application partitioning” as opposed to “Database partitioning”. Because it is based on a shared-nothing architecture, it it natively more scalable than a shared-everything approach (as in Oracle RAC).

Java Platform Standard Edition 7

Initially released in 1995, the programming language Java started a revolution in computer languages because of the concept of Java Virtual Machine causing instant portability across computer architectures. While the 1.7 JVM is still in beta release, it is the base of my iGenOltpMysql Java class performing the workload shown in this article. The key enhancement of the JVM 1.6 was the introduction of native Dtrace probes. The 1.7 JDK is an update packed with performance related enhancements including an improved Adaptive Compiler, optimized Rapid Memory Allocation , finely tuned garbage collector algorithms and finally a lighter thread synchronization capability causing better scalability. For this article we used the JDK7 build 38.

Software and Hardware summary

This study is using Solaris 10 Update 6 (released October 31st,2008), Java 1.7 build 38 (released Otober 23rd,2008), SLAMD 1.8.2, iGenOLTP v4.2 for MySQL and MySQL 5.1.29. The hardware tested is a T5440 with 4xUltraSPARC T2 Plus 1.2Ghz and 64 GB of RAM . A Sun Blade 8000 with 10 blades each with 2xAMD Opteron 8220 2.8Ghz and 8GB RAM is used as a client system. Finally a Sun ST6140 storage array [with 10x146GB 15k RPM drives] is configured in RAID-1 [2 HS], with two physical volumes and connected to the T54440 with two 4GB/s controllers.

Scaling vertically first

This is a matter of methodology. The first step is to determine the peak throughput of a single instance of MySQL with iGenOLTP using InnoDB then use approximately 75% of this throughput as the basis for the horizontal scalability test. ZFS and MySQL current best practices guided the choice of all the tunables used. [available upon request] The test is done in stabilized load with each simulation thread executing 10 transactions per second. Please find below the throughput and response time scalability curves :

Note that the peak throughput is 725 transactions per second which corresponds to 4350 SQL statements per second. We are caching the entire 1 Gbyte database. The only I/Os happening are due to the delete/insert statements, the MySQL log and the ZFS Intent Log. We will be using 75% of the peak workload simulation as the base workload per instance for the horizontal scalability exercise. Why 75% ? Our preliminary tests showed that it the was the best compromise to reach maximum multi-instance throughput.

Scaling horizontally

The next step was to increase the number of instances while increasing proportionally the database size (number of customer ids). We will have the same 600 TPS workload requested on each instance but querying a different range within the global data set. The beauty of the setup is that we do not have to reinstall the MySQL binaries multiple times : we could just use soft links. The main thing to do was to configure 32 ZFS file systems on our ZFS pool and then to create & load the databases. This was easily automated with ksh scripts. Finally, we had to customize the Java workload to query all the database instances accurately...

Here are the results :

As you can see, we were able to reach a peak of more than 79,000 SQL queries per second on a single 4 RU server. The transaction throughput is still increasing after 28 instances but this is the sweet spot for this benchmark on the T5440 as guided by the transactions average response time. At 28 instances, we observed less than 30ms average response time. However, for 32 instances, response times jumped to an average of 95ms.

The main trick to achieve horizontal scalability: Optimize thread scheduling

Solaris is using the timeshare class as the default scheduling class. The scheduler needs to always make sure that the thread priorities are adequately balanced. For this test, we are running thousand of threads running this workload and can get critical CPU User Time back by avoiding unnecessary work by the scheduler. To achieve this, we are running the MySQL engines and Java processes in the Fixed Priority class. This is achieved easily using the Solaris priocntl command.

As I mentioned in introduction, an architecture shift is happening. Database sharding and application partitioning are the foundation of future information systems as pioneered by companies like Facebook [see this interesting blog entry]. This article prove that Sun Microsystems servers with CoolThread technology are an exceptional foundation for this change. And they will also considerably lower your Total Cost of Ownership as illustrated in this customer success story.

A very special thank you to the following experts who helped in the process or reviewed this article : Huon Sok, Allan Packer, Phil Morris, Mark Mulligan, Linda Kateley, Kevin Figiel and Patrick Cyril.

See you next time in the wonderful world of benchmarking....

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Tuesday May 20, 2008

The Hare and the Tortoise [X6250 vs T6320] or [INTEL XEON E5410 vs SUN UltraSPARC-T2 ]

The Hare and The Tortoise
View Benoit's profile on LinkedIn

"To win a race the swiftness of a dart ... Availeth not without a timely start"


The tree on yonder hill we spy [Sun Blade 6000
Modular Systems]
The Sun Blade 6000 chassis support up to ten blades in a ten rack-unit chassis and is extremely popular due to its versatility. In fact, you can test your application today on four different chips within the same chassis. (UltraSPARC-T1 [T6300], UltraSPARC-T2 [T6320], AMD Opteron dual-core [X6220] and INTEL Xeon dual-core and quad-core [X6250]. While the Opteron and T1 blades have performance characteristics well defined by now, I was really curious to see how the new T2 blade will perform when compared to the Xeon Quad-Core.

A grain or two of hellebore [Chips & Systems]
In term of chips details, the T2 and Xeon are diverging. The three key differences are the total number of strands [16 times for the T2], the CPU frequency [1.66 times more for the Xeon] and the L2 cache size [3 times more for the Xeon].

This simple table illustrate their key characteristics :

INTEL Xeon E5410
45 nm
65 nm
820 million
500 million
Total #strands
L1 cache
16KB I. + 16KB D.
16KB I. + 8KB D.
L2 cache
12 MB
4 MB
Nominal Power
80 W
95 W

This table makes it clear that predicting response time or throughput  delta between this two chips is a risky endeavor !


Following this two pictures [X6250 and T6320], here is our hardware list :

Role Model
System clock
T2 blade
32 GB
Xeon blade
1333 Mhz
32 GB
1000 Mhz
8 GB

I dare you to the wager still [Benchmarks]
I ran several benchmarks (including Oracle workloads) on all type of blades, but for the purpose of this article I will present only the two simple micro-benchmarks iGenCPU and iGenRAM.

The iGenCPU benchmark is a JavaTM-based CPU micro-benchmark used to compare the CPU performance of different systems. Based on a customized Java complex number library, the code is computing Benoit Mandelbrot's highly dense fractal structure using integer and floating-point calculations. (50%/50%) The simplicity of the code as well as its non-recursivity allow a very scalable behavior using less than 128 Kb of memory per thread. The exact throughput in number of fractals per second and average response times are reported and coalesced for each scalability level.

The iGenRAM benchmark is based on the California lotto requirements. The main purpose of this workload is to measure multi-threaded memory allocation and multi-threaded memory searches in Java. The first step of the benchmark is for each thread to allocate 512 Megabytes of memory in a 3-dimensional integer arrays. The second step is to search through this memory to determine the winning tickets. The exact throughput in lotto tickets per millisecond as well as the average allocation and search time are reported and coalesced for each scalability level.

 For this test, we used Solaris 10 Update 4 and Java version 1.6.1.

And list wich way the zephyr blows [Results]

Here are the iGenCPU throughput & response time :


Notes :

1-The Hare [X6250] is starting very fast but gets tired at 8 threads and really slow down at 12 threads
2-The Tortoise [T6320] reach more than twice the throughput of the Hare at 60 threads.
3-Single threaded average transaction response time is two times better on the Hare.

Now let's look at the iGenRAM results :


Notes :

1-Phenomenal memory throughput of the Hare [X6250] at low level of threads. But in peak, the Tortoise [T6320] achieve 11% more throughput
2-When the Hare is giving up (~7 threads), the Tortoise is just warming up, reaching its peak throughput at about 40 threads.
3-Single-threaded, it takes 9 ms to allocate 512 Mb on the Hare, 33 ms to do the same thing on the Tortoise.
4-Single-threaded, it takes 5 ms to search through 512 Mb on the Hare, 34 ms to do the same thing on the Tortoise.


The race is by the tortoise won.
Cries she, "My senses do I lack ?
What boots your boasted swiftness now ?
You're beat ! and yet you must allow,
I bore my house upon my back."

See you next time in the wonderful world of benchmarking....
Special thanks to Mr Jean De La Fontaine [1621-1695]

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Wednesday Nov 14, 2007

OLTP performance of the Sun SPARC Enterprise M9000 on Solaris 10 08/07

I recently published a performance comparison of the Sun Fire E25k and the new Sun SPARC Enterprise M9000.
 In this article, a lot of my readers noticed the following note :
"Oracle OLTP is disappointing on the M9000 with an increase in response time at peak throughput. Upcoming release of Solaris and Oracle 10g should improve this result"

Critical bug fixes

 The reason why I wrote this is because I knew that Sun engineering was working hard at fixing three key performance bugs specific to database performance on any of the M-serie systems. Here is a list of this bugs that were successfully fixed in Solaris 10 08/07 (Update 4) :

1. Bug 6451741
SPARC64 VI prefetch tuning needs to be completed
Impact : L2 cache efficiency is key to database memory performance. Corrected preferch values improve memory read and write performance.

2. Bug 6486343
Mutex performance on large M-serie system need improvement
Impact : The mutex retry and backoff algorithm needed to be retuned for M-series system due to out-of-order execution and platform specific branch prediction routines. Also improve lock concurrency on hot mermory pages

3. Bug 6487440
Memory copy operations needs tuning on M-serie systems
Impact : The least important fix but important for Oracle stored procedures , triggers and constraints

The big question was : How much of an improvement it would have on OLTP performance ?
Well, one thing is sure is that your mileage may vary but I measured on my workload a whooping 1.33
 lower response times for 1.38 faster throughput (compared to Solaris 10 Update 3) . It is also interesting to notice that all the other workloads tested have not moved significantly as they are not really sensitive to the issues tackled there.

Please find below the corrected comparative charts in throughput and response time after a reminder on the workloads :

Java workloads

Not exactly.So let's try to be a little bit more specific using five different 100% Java (1.6) workloads :
  1. iGenCPU v3 - Fractal simulation 50% Integer / 50% floating point
  2. iGenRAM v3 - Lotto simulation (Memory allocation and search
  3. iGenBATCH v2 - Oracle 10g batch using partionning, triggers, stored procedures and sequences
  4. iGenOLTP v4 -(Heavy-weight OLTP


The values showed hare are peak results obtained by building the complete scalability curve. The response times mentioned are average, at peak and in Milliseconds.


Throughput RT (ms) Throughput RT (ms)
iGenCPU v3 303 fractals/second 105 728 fractals/second 44
iGenRAM v3 2865 lottos/ms 55 4881 lottos/ms 17
iGenBatch v2 35 TPS 907 50 TPS 626
iGenOLTP v4 3938 TPM 271 6194 TPM 264

As we are trying to compare to the frequency 1.267 factor, let's look at those results  by giving a factor 1 to the E25k.

First, here is throughput :

Throughput E25k M9000
'iGenCPU v3 1 2.403
'iGenRAM v3 1 1.704
'iGenBATCH v2 1 1.450
'iGenOLTP v4 1 1.573
Frequency 1 1.267

Which would be this chart :


And here is the average  reponse time at peak throughput (still using a base 1 for the E25k) :

RT E25k M9000
iGenCPU v3 1 0.419
iGenRAM v3 1 0.301
iGenBATCH v2 1 0.690
iGenOLTP v4 1 0.970

And the chart :


This new numbers are illustrating how well placed are the M-serie servers to replace the current UltraSPARC-IV servers, from the smallest Sun Fire V490 to the largest Sun Fire E25k...As long as you use at least Solaris 10 08/07 .

See you next time in the wonderful world of benchmarking...

Monday Sep 17, 2007

Solaris Vista dual-boot : No problem !

Solaris Vista dual-boot I am glad to report that I just successfully & flawlessly installed Solaris Nevada b72 and Vista Ultimate on a Ferrari 5000 laptop.

Summary of the operations :

1. The laptop had already Vista installed in C: (70G) with a D: partition (70G)
2. Using the Vista Disk Partitioner (default System tool in Vista Ultimate), I removed the D: partition
3. I downloaded Solaris Nevada build 72 and burned a DVD-R
4. I went in the Setup menu of the Ferrari 5000 and allowed boot only from the DVD
5. I booted Solaris b72 and chose the option (3) Terminal
6. I partition my disk to create a single Solaris partition with :
fdisk /dev/rdsk/c0d0p0
7.  Reboot and installed Solaris. Installation was about 50 minutes.
8. Booted again from the DVD . Chose option (3)
9. Modified /a/boot/grub/menu.lst by adding :
title Windows Vista
rootnoverify (hd0,1)
chainloader +1
10. Went back in the boot menu (F2) and re-enable disk booting.
11. Rebooted and verified that I could use Solaris & Vista.
12. Booted Solaris, installed SLAMD and the iGen benchmark suite
13. Ran the iGenCPU benchmark to compare the system to others. Got 27 fractals/second at 4 threads. Nice for a laptop !

Additional note : Wireless configuration is now very easy as the wificonfig tool is part of the Nevada distribution
The only thing needed is update_drv -a -i '"pciex168,1c"' ath . No reboot necessary.
Then you can do wificonfig -i ath0 plumb ; wificonfig -i ath0 scan

Final note : All the tricks that you can found in other blogs are now irrelevant as the MBR Solaris bug was bixed in build 70.

Monday Aug 20, 2007

Sun SPARC Enterprise M9000 vs Sun Fire E25k - Datapoints

Sun SPARC Enterprise M9000 vs Sun Fire E25k - Datapoints
A performance comparison of two high-end UNIX servers using the iGen benchmark suite
[Read More]

Wednesday Nov 08, 2006

Unbreakable Oracle 10g Release 2 : What if you have ORA-600 kcratr1_lastbwr ?

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This an interesting story that happened yesterday on one of our customer site. An engineer powered off the wrong rack of equipment containing a Sun Fire X4600 running Oracle 10g Release 2.  Almost no transactions were performed at time so when the system came up the customer expected the database to be up and running very quickly.

In reality this is what happened :

Tue Nov  7 11:19:42 2006
Tue Nov  7 11:19:42 2006
Beginning crash recovery of 1 threads
 parallel recovery started with 16 processes
Tue Nov  7 11:19:44 2006
Started redo scan
Tue Nov  7 11:19:44 2006
Errors in file /xxx/oracle/oracle/product/10.2.0/db_1/admin/xxx/udump/xxx_ora_947.trc:
ORA-00600: internal error code, arguments: [kcratr1_lastbwr], [], [], [], [], [], [], []
Tue Nov  7 11:19:44 2006
Aborting crash recovery due to error 600
Tue Nov  7 11:19:44 2006
Errors in file /xxx/oracle/oracle/product/10.2.0/db_1/admin/xxxtest/udump/xxxtest_ora_947.trc:
ORA-00600: internal error code, arguments: [kcratr1_lastbwr], [], [], [], [], [], [], []
ORA-600 signalled during: ALTER DATABASE OPEN...

Not too pretty ! Checking the ASM configuration and the IO subsystem showed nothing wrong. So what to do if you do not have a backup handy ?

Well, here is the idea .... what would we do if we had a backup that was inconsistent ?
The recover database command will start an Oracle process which will roll forward all transactions stored in the restored archived logs necessary to make the database consistent again. The recovery process must run up to a point that corresponds with the time just before the error occurred after which the log sequence must be reset to prevent any further system changes from being applied to the database.

So we tried :

startup mount

Tue Nov  7 11:54:03 2006
Starting background process ASMB
ASMB started with pid=61, OS id=1070
Starting background process RBAL
RBAL started with pid=67, OS id=1074
Tue Nov  7 11:54:13 2006
SUCCESS: diskgroup xxxTESTDATA was mounted
Tue Nov  7 11:54:17 2006
Setting recovery target incarnation to 2
Tue Nov  7 11:54:17 2006
Successful mount of redo thread 1, with mount id 2364224219
Tue Nov  7 11:54:17 2006
Database mounted in Exclusive Mode
Tue Nov  7 11:54:32 2006

recover database

Tue Nov  7 11:54:32 2006
Media Recovery Start
 parallel recovery started with 16 processes
Tue Nov  7 11:54:33 2006
Recovery of Online Redo Log: Thread 1 Group 3 Seq 4 Reading mem 0
  Mem# 0 errs 0: +xxxTESTDATA/xxxtest/onlinelog/group_3.263.605819131
Tue Nov  7 11:59:25 2006
Media Recovery Complete (xxxtest)
Tue Nov  7 11:59:27 2006
Completed: ALTER DATABASE RECOVER  database 

alter database open

Tue Nov  7 12:03:01 2006
alter database open
Tue Nov  7 12:03:01 2006
Beginning crash recovery of 1 threads
 parallel recovery started with 16 processes
Tue Nov  7 12:03:01 2006
Started redo scan
Tue Nov  7 12:03:01 2006
Completed redo scan
 273 redo blocks read, 0 data blocks need recovery
Tue Nov  7 12:03:01 2006
Started redo application at
 Thread 1: logseq 4, block 12858574
Tue Nov  7 12:03:01 2006
Recovery of Online Redo Log: Thread 1 Group 3 Seq 4 Reading mem 0
  Mem# 0 errs 0: +xxxTESTDATA/xxxtest/onlinelog/group_3.263.605819131
Tue Nov  7 12:03:01 2006
Completed redo application
Tue Nov  7 12:03:01 2006
Completed crash recovery at
 Thread 1: logseq 4, block 12858847, scn 824040
 0 data blocks read, 0 data blocks written, 273 redo blocks read
Tue Nov  7 12:03:02 2006
Thread 1 advanced to log sequence 5
Thread 1 opened at log sequence 5
  Current log# 1 seq# 5 mem# 0: +xxxTESTDATA/xxxtest/onlinelog/group_1.261.605819081
Successful open of redo thread 1
Tue Nov  7 12:03:02 2006
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Tue Nov  7 12:03:02 2006
SMON: enabling cache recovery
Tue Nov  7 12:03:03 2006
Successfully onlined Undo Tablespace 1.
Tue Nov  7 12:03:03 2006
SMON: enabling tx recovery
Tue Nov  7 12:03:03 2006
Database Characterset is UTF8
replication_dependency_tracking turned off (no async multimaster replication found)
Starting background process QMNC
QMNC started with pid=56, OS id=1128
Tue Nov  7 12:03:05 2006
Completed: alter database open

And we are up and running ! The real thing that Oracle should work on is the quality and clarity of their error messages.
At this point this is quite poor ...

 Unbreakable database, maybe. Automatic (and simple) , not yet.




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