High System or Kernel Memory Usage

[Michael Steele_2]

Don:

You do see that there's an oracle database on this box. So beside putting the O/S into an unknown state, you also want to use uncertified by oracle kernel parameters.

Are you even aware that oracle provides kernel parameters settings for the HP-UX O/S, as this is what they have tested and certified and recommend for working best with their products?

Do you even have a HP server that you administrate? Or is there some virtual box out their that exists on paper and got built based upon assorted university text books and internet whitepapers?

Let's take another example, SAP. Ever worked with an SAP server before or a team of basis administrator's?

[kenj_2]

Following up on Don's comment about the asyncdsk arena looking high in the kernel. In fact there is a known problem with this issue on Oracle 11g. The problem is documented in Oracle bug 8965438. A fix is planned by Oracle, but is not available at the present time.

On Oracle 10g, when Oracle configures each asyncdsk port for a process, it sets the max_concurrent value for most of the asyncdsk ports to 128. This max_concurrent value limits the number of parallel I/Os to a given asyncdsk port to 128. The asyncdsk driver then allocates a buffer header for each of the potential 128 I/Os. Each buffer header is 896 bytes, resulting in approximately 128*896 bytes, or 112 Kb per asyncdsk port. Typically, each Oracle process (shadow processes, dbwriters, logwriter, etc) will have one asyncdsk port open. So if there are 1000 processes, then the memory used by the asyncdsk driver is ~110 MB.

On Oracle 11g, Oracle uses a max_concurrent value of 4096, which results in 4096*896 bytes or 3.5 MB per asyncdsk port. So if there are 1000 Oracle processes, the asyncdsk driver can consume ~3.5 GB of memory. Also, due to the large and odd sized kernel memory allocation, the kernel's Super Page Pool becomes fragmented and also consumes large amounts of memory.

Ken Johnson
HP

[Michael Steele_2]

And given what HP support is today, citations and references and web links please, else, ....

[RahulS]

For time being I have added extra 16GB RAM on each of the DB nodes, to augment the high memory usage.

Thanks Michael, Dennis, Emil, Wayne, Don for your valuable suggestions.

[Horia Chirculescu]

And your problems vanished only by adding extra memory?

Horia.

[Dennis Handly]

>Thanks Michael, Dennis, Emil, Wayne, Don for your valuable suggestions.

If you are happy with all of the answers you got, please read the following about how to assign points:
http://forums.itrc.hp.com/service/forums/helptips.do?#33

[RahulS]

After memory upgrade, application is running fine.