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Understanding CPU on AIX Power SMT Systems

This month I worked with a chicagoland company to improve performance for eBusiness Suite on AIX. I’ve worked with databases running on AIX a number of times over the years now. Nevertheless, I got thrown for a loop this week.

TLDR: In the end, it came down to a fundamental change in resource accounting that IBM introduced with the POWER7 processor in 2010. The bottom line is twofold:

Understanding CPU on AIX Power SMT Systems

This month I worked with a chicagoland company to improve performance for eBusiness Suite on AIX. I’ve worked with databases running on AIX a number of times over the years now. Nevertheless, I got thrown for a loop this week.

TLDR: In the end, it came down to a fundamental change in resource accounting that IBM introduced with the POWER7 processor in 2010. The bottom line is twofold:

Understanding CPU on AIX Power SMT Systems

This month I worked with a chicagoland company to improve performance for eBusiness Suite on AIX. I’ve worked with databases running on AIX a number of times over the years now. Nevertheless, I got thrown for a loop this week.

TLDR: In the end, it came down to a fundamental change in resource accounting that IBM introduced with the POWER7 processor in 2010. The bottom line is twofold:

n/a

Oracle on AIX - where's my cpu time ?

This story begins couple of weeks ago when I was asked to look on performance problem for critical processes before go-live. There were differences between run times between different test systems and between runs with 10046 trace enabled or not.

Oracle on AIX - where's my cpu time ?

This story begins couple of weeks ago when I was asked to look on performance problem for critical processes before go-live. There were differences between run times between different test systems and between runs with 10046 trace enabled or not.

Limit nmon to certain disks

I am often working on systems with large number of LUNs, going into the hundreds. Trying to keep track is difficult at best. Sometimes though you might want to limit yourself to a specific number of disks-I knew about the dskfilt option in collectl but only today learned about a similar feature in nmon. The following is a very greatly simplified example of course, but it gives you the idea.

Assume you are interested in 4 disks-sd{a,b,c,d}. Let’s further assume that your disks are used for 2 ASM disk groups, DATA and RECO. You could create a file “disks.dat” with the following contents:

DATA sda sdb
RECO sdc sdd

Then pass that file to nmon with the -g flag. When you type “g” now, you are shown IO stats for those disks.

Frightening number of linking errors for 11.2.0.1.3 on AIX 5.3 TL11

I just applied PSU 3 for 11.2.0.1 on AIX 5.3 TL11. That would have been more straight forward, had  there not been a host of errors when relinking oracle. There were loads of these:

SEVERE:OPatch invoked as follows: 'apply '
INFO:
Oracle Home       : /u01/app/oracle/product/11.2.0.1
Central Inventory : /u01/app/oracle/product/oraInventory
 from           : /etc/oraInst.loc
OPatch version    : 11.2.0.1.3
OUI version       : 11.2.0.1.0
OUI location      : /u01/app/oracle/product/11.2.0.1/oui
Log file location : /u01/app/oracle/product/11.2.0.1/cfgtoollogs/opatch/opatch2010-11-01_09-28-22AM.log
...
[more output]
...
INFO:Running make for target ioracle
INFO:Start invoking 'make' at Mon Nov 01 09:29:26 GMT 2010Mon Nov 01 09:29:26 GMT 2010
INFO:Finish invoking 'make' at Mon Nov 01 09:29:40 GMT 2010
WARNING:OUI-67215:
OPatch found the word "error" in the stderr of the make command.
Please look at this stderr. You can re-run this make command.
Stderr output:
ld: 0711-415 WARNING: Symbol ldxdts is already exported.
ld: 0711-415 WARNING: Symbol ldxsto is already exported.
ld: 0711-415 WARNING: Symbol lnxadd is already exported.
...
ld: 0711-319 WARNING: Exported symbol not defined: cout__3std
...
ld: 0711-224 WARNING: Duplicate symbol: .kotgscid
...
ld: 0711-783 WARNING: TOC overflow. TOC size: 219488    Maximum size: 65536
 Extra instructions are being generated for each reference to a TOC
 symbol if the symbol is in the TOC overflow area.

Wow, that looked like a completely corrupted installation of Oracle now, and I got ready to roll the change back. However, MOS had an answer to this!

These errors can be ignored as per this MOS document: Relinking causes many warning on AIX [ID 1189533.1]. See also MOS note Note 245372.1 TOC overflow Warning Can Safely Be Ignored and BUG:9828407 – TOO MANY WARNING MESSAGES WHEN INSTALLING ORACLE 11.2 for more information.

Oracle Database 11g Release 2 for HP-UX Itanium and AIX (PPC64) Now Available

The HP-UX Itanium and AIX (PPC64) ports of Oracle Database 11g Release 2 can now be downloaded from OTN. Happy Holidays!!! Tweet This Post

Knowing the trend of Deadlock occurrences from the Alert Log

Recently, my client deployed a new application and had this intermittent “Deadlock Storm” …

A trace file was sent and I was able to pinpoint the cause of the deadlock and the session that caused it.
The deadlock was a TX enqueue with mode of 4 (S – share) which could be verified by looking at the following lines of the Process State dump:

   last wait for 'enq: TX - row lock contention' blocking sess=0x 7000000cb239d60 seq=7849 wait_time=2929705 seconds since wait started=3
            name|mode=54580004, usn<<16 | slot=a0028, sequence=283f2

the "enqueue and lock mode" is explained as:
mode=54580004 (see above)
5458 (hex) = TX (ascii)
0004 (hex) = mode 4 (S – share)