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System Hangs / Crashes when Shared Memory Segment is deleted

System Hangs / Crashes when Shared Memory Segment is deleted

I have a 3.8Gb Oracle SGA running on HP-UX v11.0 [64bit] and Oracle8 v8.1.7.0.0. The SGA sits into a single Shared Memory Segment which SHMMAX set at 4Gb.

When I issue the Oracle 'SHUTDOWN' command, the Shared Memory Segment is marked for deletion, and when I exit sqlplus, HP-UX should delete the Shared Memory Segment.

My problem is that usually (3 out of 4), the HP server crashes when presumably trying to delete the shared memory segment. In a script, I can issue 2 'ipcs -asmb | grep oracle' commands for the HP server crashes.

We are in talks with HP with regards to the crash dump, but has anyone come across this behaviour before.

TIA
Andrew
3 REPLIES
Steven Sim Kok Leong
Honored Contributor

Re: System Hangs / Crashes when Shared Memory Segment is deleted

Hi,

We have Oracle 8.0.6 on HP-UX 11 (64-bit), 2 GB shmmax. Had no problems shutting down Oracle.

Was there any crash dump in /var/adm/crash? Has it been analyzed? Was an STM exercise test performed on the physical memory to verify that there was no hardware problems? Do you have other applications that utilises shared memory running in the system? Has your /var/adm/syslog/syslog.log been checked for any vmunix error messages? Has your /etc/shutdownlog been checked for any panic strings? Has your /var/tombstones been checked?

Hope this helps. Regards.

Steven Sim Kok Leong
Brainbench MVP for Unix Admin
http://www.brainbench.com
Email: steven@beepz.com. Homepage: https://www.beepz.com

Re: System Hangs / Crashes when Shared Memory Segment is deleted

Hi,

Thanks for the feedback, and the updates are as follows;
1. We are capable of running Oracle DBMS's with smaller SGA's without problems, it is only when we work with the 3.8Gb SGA that we run into problems.

Our SysAdmin is working with HP to analyze the crash dump, but unfortunately, it is only a partial dump.

I am not sure what an STM exercise test is, but I will talk with the SysAdmin for this.

syslog.log is reset at each boot time, unfortunately, but what I will do is run a tail on syslog.log and the other log files you mention and run the test again.

/etc/shutdownlog does show panic strings. I'll talk with the SysAdmin to make sure she has seen them.

/var/tombstones - There is a ts99 for the time that the system crashed, again, I'll talk with the SysAdmin.

Thanks for your assistanec, and hopefully we have a way forward.

Andrew
Maddy van der Bokke
Occasional Contributor

Re: System Hangs / Crashes when Shared Memory Segment is deleted

You are correct in that syslog.log is rewritten on each reboot, but the previous version is written to OLDsyslog.log in the same directory /var/adm/syslog. You may want to look at that for information as well.