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Instance Hangs After Dynamic CPU Changes (Doc ID 832842.1)

Last updated on NOVEMBER 28, 2016

Applies to:

Oracle Server - Enterprise Edition - Version:
This problem can occur on any platform.


This issue was observed on Oracle on a HP-UX Itanium server.

Problem description:
1. Database hangs. No new connections are allowed.
2. When trying to connect as sysdba, get these errors:
          ERROR:ORA-01034: ORACLE not available
          ORA-27123: unable to attach to shared memory segment
          HPUX-ia64 Error: 22: Invalid argument
3. Have to shutdown abort.

The alert log shows no errors, but does show some CPU count changes prior to the hang:
Wed May 6 10:46:58 2009
Detected change in CPU count to 5
Wed May 6 10:46:58 2009
Resource Manager cpu_count => Low Threshold (6) : High Threshold (8)
Wed May 6 10:47:23 2009
Process q001 died, see its trace file
. . .  . .
Detected change in CPU count to 7
Detected CPU count 7 higher than the allowed maximum (6), capped (3 times CPU count at instance startup)

Specifically, the alert log will show that the CPU_COUNT exceeded the allowed maximum.


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