DISM in 11.2.0.2 on Solaris 10

  • From: "Hameed, Amir" <Amir.Hameed@xxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 19 Jul 2011 09:59:03 -0400

I have a two-node Oracle RAC 11.2.0.2 environment running multiple
databases on M3000 servers. Both servers are identical in configuration
with the exception that server A has twice the amount of physical memory
than server B (64GB versus 32GB). The following parameters are NOT set
in the SPFILE and therefore, DISM should not be enabled:

 

SGA_TARGET

SGA_MAX_SIZE

MEMORY_MAX_TARGET

MEMORY_TARGET

 

However, when I run the "ps" command at the OS, I observe the following:

 

Node A:

ps -ef|grep svt2d1|grep dism

    root 13751     1   0 21:42:51 ?           0:00 ora_dism_svt2d101

    root 13762     1   0 21:42:53 ?           0:00 ora_dism_svt2d101

    root 13740     1   0 21:42:38 ?           0:00 ora_dism_svt2d101

    root 13745     1   0 21:42:49 ?           0:00 ora_dism_svt2d101

 

Node B:

ps -ef|grep svt2d1|grep dism

    root  7517     1   0 21:42:33 ?           0:00 ora_dism_svt2d102

    root  7523     1   0 21:42:42 ?           0:00 ora_dism_svt2d102

 

So, node A has twice the number of DISM processes running than node B.
Based on my past experience with DISM with the previous Oracle database
versions, I have seen only one DISM process running per instance and
even in those situations, if the INIT parameters that impact DISM are
turned off, no DISM process was found running.

 

 

In the above RAC environment, when I run the "pmap" command, I see that
the shared memory segment is using ISM as shown below:

ps -ef|grep svt2d|grep pmon

  oracle 13653     1   0 21:42:08 ?           0:13 ora_pmon_svt2d101

 

pmap -xs 13653 | grep ism

0000000380000000    1261568    1261568          -    1261568   4M rwxsR
[ ism shmid=0x7b00005f ]

00000003CD000000          8          8          -          8   8K rwxsR
[ ism shmid=0x7b00005f ]

 

So, based on the "pmap" command, it seems that DISM is turned OFF.

 

To conclude, the following was observed in a two-node 11.2.0.2 RAC
running on Solaris 10:

-       With the database INIT parameters that enable DISM not set, DISM
processes were found running on the server.

-       There were more than one DISM processes running for each
instance.

-       Server with twice the amount of RAM had spawned twice the number
of DISM processes than the one with half the amount of RAM.

-       The "pmap" command showed that the instance was actually using
ISM.

 

Has anyone made similar observations related to DISM in 11.2.0.2?

 

Thanks

Amir

 

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