• Article Type: General
• Product: Aleph
• Product Version: 20

Description:
Our DBAs want to modify kernel parameters to improve performance on our production and test servers. We received this question:

"For a permanent solution to this, I would like to remove the kernel parameter project.max-shm-memory and the project group.dba from both loon and libprd. We would do it on loon one week and libprd the next. But before we do this, we should verify with Ex Libris that they do not require these settings."

Are the settings required?

Resolution:
[From Ex Libris:] The solution to the problem according to Oracle is this (Doc ID 1147673.1):
"Solution: The warning message seen here on startup, indicates that Oracle was not able to allocate all of the SGA memory in a single shared memory segment in the operating system. This is not fatal as oracle will then simply try to create multiple smaller segments to hold the SGA. The fact that multiple segments need to be used though can impact performance and so it is better to increase your servers SHMMAX kernel parameter to be larger than the maximum size of the Oracle SGA (MAX_MEMORY_TARGET or SGA_MAX_SIZE).
Please note that for Solaris, you also need to set the PROJECT.MAX-SHM-MEMORY kernel parameter as well to prevent this warning message occurring. The PROJECT.MAX-SHM-MEMORY should be set larger than the sum of all segments used by the project."

[From site:] Our DBA reports that the problem, i.e., the ARC database not starting, only occurred after a cold backup. We have revised our backup procedures and are doing a hot RMAN backup instead. Any database restarts will monitored by a DBA, who will verify that the database comes back up.

With the above in mind, we are dropping the kernel parameter change at this time. We will revisit the issue if we run into database startup problems again.

• Article last edited: 10/8/2013