Monday May 11, 2009
Monday May 11, 2009
Running your Oracle database on internal Solid State Disks : a good idea ?
Solid State Disks : a 2009 fashion
This technology is not new : it originates in 1874 when a German physicist named Karl Braun (pictured above) discovered that he could rectify alternating current with a point-contact semiconductor. Three years later, he had built the first CRT oscilloscope and four years later, he had built the first prototype of a Cat's whisker diode, later optimized by G. Marconi and G. Pickard. In 1909, K. Braun shared the Nobel Prize for physics with G. Marconi.
The Cat's whisker diodes are considered the first solid state devices. But it is only in the 1970s that they appeared in high-end mainframes produced by Amdahl and Cray Research. However, their high-cost of fabrication limited their industrialization. Several companies attempted later to introduce the technology to the mass market including StorageTek, Sharp and M-systems. But the market was not ready.
Nowadays, SSDs are composed of one of two technologies : DRAM volatile memory or NAND-flash non-volatile memory. Key recent announcements from Sun (Amber road and ZFS), HP (IO Accelerator) and Texas Instruments (Ram San 620) as well as lower cost of fabrication and larger capacities are making the NAND based technology a must-try for every company this year.
This article is looking at the Oracle database performance of our new 32Gbytes SSDs OEM'd from Intel. This new devices have improved their I/O capacity and MTBF with an architecture featuring 10 parallel NAND flash channels. See this announcement for more.
If you dig a little bit on the question, you will find this whitepaper . However, the 35% boost in performance that they measured seems insufficient to justify trashing HDDs for SSDs. In addition, as they compare a different number of HDDs and SSDs, it is very hard to determine the impact of a one-to-one replacement. Let's make our own observations.
Here is a picture of the SSD tested – thanks to Emie for the shot !
Goals
As any DBA knows, it is very difficult to characterize a database workload in general. We are all very familiar with the famous “Your mileage may vary” or “All customer database workloads are different”. And we can not trust Marketing department on SSDs performance claims because nobody is running a synthetic I/O generator for a living. What we need to determine is the impact for End-Users (Response time anyone ?) and how the Capacity Planners can benefit from the technology (How about Peak Throughput ?).
My plan is to perform two tests on a Sun Blade X6270 (Nehalem-based) equipped with two Xeon chips and 32Gb of RAM on one SSD and one HDD- with different expectations.
Create a 16 Gigabytes database that will be entirely cached in the Oracle SGA. Will we observe any difference ?
Create a 50 Gigabytes database that can only be cached about 50% of the time. We expect a significant performance impact. But how much ?
SLAMD and iGenOLTP
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 http://www.slamd.com/.
It is also available as a java.net
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.
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 for Oracle and Oracle 10.2.0.2. The hardware tested is a Sun Blade X6270 with 2xINTEL XEON X5560 2.8Ghz and 32 GB of DDR3 RAM . This blade has four standard 2.5 inches disks slots in which we are installing 1x32 Gbytes Sun/Intel SSD and 1x146Gb 10k RPM SEAGATE-ST914602SS drive with read-cache and write-cache enabled.
Test 1 – Database mostly in memory
We are creating a 16 Gigabytes database (4k block size) on one Solid State Disk and on one Seagate HDD configured in one ZFS pool with the default block size. We are limiting the ZFS buffer cache to 1 Gigabytes and allow an Oracle SGA of 24 Gigabytes. All the database will be cached. We will feel the SSD impact only on random writes (about 10% of the I/O operations) and sequential writes (Oracle redo log). The test will become CPU bound as we increase concurrency. We are testing from 1 to 20 client threads (I.e database connections) in streams.
In this case and for Throughput [in Transactions per second], the difference between HDD and SSD are evoluting from significant to modest when concurrency increase. In fact, this is interestingly in the midrange of the scalability curve that we observe a peak of 71% more throughput on the SSD (at 4 threads). At 20 threads, we are mostly CPU bound, therefore the impact of the storage type is minimal and the SSD impact on throughput is only 9%.
For response times [in milliseconds], it is slightly lower with 42% better response times at 4 threads and 8% better at 20 threads.
Test 2 – Database mostly on disk
This time, we are creating a 50 Gigabytes database on one SSD and on one HDD configured in their dedicated ZFS pool. Memory usage will be sliced the same way than test 1 but will not be able to cache more than 50% of the entire database. As a result, we will become I/O bound before we become CPU bound. Please remember that the X6270 is equipped with two eight-threads X5560 - a very decent 16-way database server !
Here are the results :
The largest difference is observed at 12 threads with more than twice the transactional throughput on the SSD. In response times (below), we observe the SSD to be 57% faster in peak and 59% faster at 8 threads.
In a nutshell
My intent for this test was to show you (for a classic Oracle lightweight OLTP workload)
the good news :
→ When I/O bound, we can replace two Seagate 10k RPM HDDs with one INTEL/SUN SSD for a similar throughput and twice faster response times
→ On a one for one basis, the response time difference by itself (up to 67%) will make your end users love you instantly !
→ Peak throughput in memory compared to the SSD is very close : in peak, we observed 821 TPS (24ms RT) in memory and 685 TPS (30ms RT) on the SSD. Very nice !
and the bad news :
→ When the workload is CPU bound, the impact of replacing your HDD by a SSD is moderate while losing a lot of capacity.
→ The cost per gigabyte need to be carefully calculated to justify the investment. Ask you Sales rep for more...
See you next time in the wonderful world of benchmarking....
Friday April 17, 2009
Sun Blade X6270 & INTEL XEON X5560 on OpenSolaris create the ultimate Directory Server
Sun Microsystems Directory Server Enterprise Edition 6.3 performance on X6270 (Nehalem)
[Read More]
Apr 17 2009, 01:36:15 PM PDT
Permalink
Tuesday March 24, 2009 As a new media to publish around Sun and my personal activities around the Sun Cloud initiative, I have created today a new blog : MrCloud.
See this entry...
I saw two clouds at morning
Tinged by the rising sun,
And in the dawn they floated on
And mingled into one.
Mar 24 2009, 03:37:45 PM PDT Permalink
Tuesday March 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....
Monday November 10, 2008
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.
Goals
Please find below my initial goals :
Reach a high throughput of SQL queries on a 256-way Sun SPARC Enterprise T5440
Do it 21st century style i.e. with MySQL and ZFS , not 20th century style i.e with OraSybInf... and VxFS
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.
SLAMD and iGenOLTP
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 http://www.slamd.com/.
It is also available as a java.net
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.
Conclusion
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....
Tuesday May 20, 2008
The Hare and the Tortoise [X6250 vs T6320] or [INTEL XEON E5410 vs SUN UltraSPARC-T2 ]
"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 :
| Feature |
INTEL
Xeon E5410 |
SUN
UltraSPARC-T2 |
| Process |
45 nm |
65 nm |
| Transistors |
820 million |
500 million |
| Cores |
4 |
8 |
| Strands/core |
1 |
8 |
| Total
#strands |
4 |
64 |
| Frequency |
2.33Ghz |
1.4Ghz |
| 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 |
Sockets@freq |
RAM |
| T2 blade |
T6320 |
N/A |
1@1.4Ghz |
32 GB |
| Xeon blade |
X6250 |
1333 Mhz |
2@2.33Ghz |
32 GB |
| Console |
X4200 |
1000 Mhz |
2@2.4Ghz |
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.
Conclusion
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]
May 20 2008, 05:32:36 PM PDT Permalink
Wednesday November 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 :
- iGenCPU v3 - Fractal simulation 50% Integer / 50% floating point
- iGenRAM v3 - Lotto simulation (Memory allocation and search
- iGenBATCH v2 - Oracle 10g batch using partionning, triggers,
stored procedures and sequences
- iGenOLTP v4 -(Heavy-weight OLTP
Datapoints
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.
| E25k | M9000 | |||
| 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...
Nov 14 2007, 05:53:42 PM PST Permalink
Monday September 17, 2007
Solaris Vista dual-boot : No problem !
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.
Sep 17 2007, 03:25:33 PM PDT Permalink
Monday August 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]
Aug 20 2007, 05:07:47 PM PDT
Permalink
Wednesday November 08, 2006
Unbreakable Oracle 10g Release 2 : What if you have ORA-600 kcratr1_lastbwr ?
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 :
Completed: ALTER
DATABASE MOUNT
Tue Nov 7 11:19:42 2006
ALTER DATABASE OPEN
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...
Tue Nov 7 11:19:42 2006
ALTER DATABASE OPEN
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
ALTER DATABASE 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
Completed: ALTER DATABASE MOUNT
Tue Nov 7 11:54:32 2006
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
Completed: ALTER DATABASE MOUNT
Tue Nov 7 11:54:32 2006
recover database
ALTER DATABASE 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
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
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.
Nov 08 2006, 04:44:44 PM PST Permalink