Thursday, November 20, 2008

??? diskmon

We find "diskmon" script on 11G

(Example on RAC): We find diskmon process run with Oracle CSS.

root      8074  4451  0 Nov18 ?        00:00:00 /bin/sh /etc/init.d/init.cssd diskmon
oracle    9994  8074  0 Nov18 ?        00:00:00 ORA_CRS_HOME/bin/diskmon.bin -d -f

About Oracle CSS daemon.
This script is supposed to exit 0 if it decides that it should not be respawned
and exit 1 if it wants to be respawned.

The purpose of diskmon is to issue SAGE Storage fence requests

on RAC:
we find diskmon folder on cluster log:


Example:  on diskmon log folder:

setsid: failed with -1/1
dskm_getenv_oracle_user: calling getpwnam_r for user oracle
dskm_getenv_oracle_user: info for user oracle complete
dskm_set_user: unable to change ownership for 
the log directory ORA_CRS_HOME/log/hostname/diskmon to user oracle, id 500, errno 1
11/20/08 14:39:12: Master Diskmon starting

Anyway on instance database, that has DSKM backgroup process:

Acts as conduit between RDBMS and ASM instances and the Master Diskmon daemon to communicate I/O Fencing information, I/O Resource Plans 
and Transaction Commit Cache information to SAGE Storage, If no SAGE storage is used, the slave diskmon process will exit silently after startup of the instance.

alert.log file:

DSKM started with pid=9, OS id=19208 

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