What is the cause of these Oracle errors? ORA-03113, etc.

[Mark Grant]

Gino,

I would imagine shmmax would need to be increased if the amount of shared memory being requested exceeds the 1GB. However, I am no oracle expert and this is the values we have set here too.

[Gino Castoldi_2]

Hi,

The SGA is 31.8MB, is this large enough?

10 points to any good answer.
TIA, Gino

[Hein van den Heuvel]

> The SGA is 31.8MB, is this large enough?

No, normally not. The only exception is a student type system with 50+ databases on a 1GB box or so.

You are giving Oracle less than 1% of your memory! As a generic guideling give Oracle as much memory (in percents) as work you expect it to do on the box. If the box only does oracle, give oracle all the memory! If Oracle is expected to use 25% of the boc, give is 25% ... as a startng poitns.

Bump block_buffers to 20,000 and shared pool to 300M and try again.

Now activate statspack and run a report over two snaps froma representive period after some stability is reached. PLEASE, Try to interpret at least the first page of the report yourself. Read it 20 times over. Then come back with specific question and quoted details from the report if need be.

Good luck!

Hein.

[John Palmer]

The actual error is:-
ORA-04031: unable to allocate 4176 bytes of shared memory ("shared pool","OPC_HIST_MESSAGES","sga heap","library cache")

This is caused by fragmentation of the shared pool (Part of the Oracle SGA).

There are patches for this type of error and you really should consider applying the 8.1.7.4 patchset.

Alternatively, you could increase the size of the shared pool, your SGA at 31.8Mb seems ridiculously small! Look at the shared_pool_size initialisation parameter (specified in bytes).

If you have access to Oracle Metalink, there are several relevant articles which give good advice on how to tune this parameter.

Regards,
John

[Gino Castoldi_2]

Hi,

Hein:
We are running a single instance of Oracle
8.1.7.3 for OpenView Operations.

Our current settings are this:
A) db_block_buffers = 550
B) shared_pool_size = 6000000
So A. should be 20,000 and B. 300,000,000.

John:
Installing patch 8.1.7.4 can be done but it
would have to be scheduled, etc. This is the first time that these types of errors occurred. Increasing the shared_pool_size seems like a good idea from what you and Hein
have said and is easier then applying a patch. (Patching is a good idea but tuning
one thing at a time seems safer and easier to implement at this point).

I make these changes to the initsid.ora file one at a time.


10 points to any good answer.
TIA, Gino

[Hein van den Heuvel]

> Our current settings are this:
> A) db_block_buffers = 550
> B) shared_pool_size = 6000000
> So A. should be 20,000 and B. 300,000,000.

Now that I see that you are using Oracle for a relatively small task I would recommend a slightly less aggresive change. 500 buffers, and 6 M shared is just not enough.

Try 2000 buffers and 50 or 100 M buffer pool for this task. Please DO change both in this specific case as they are way low.

The final choice also depend on the overall system contention for memory resources.

Please doublecheck the openview doc for minimal Oracle setup guideance... surely there is some indicator?

Hein.

[Indira Aramandla]

Hi TIA,

The problem is reported with the size allocation in shared pool. Please validate the shared pool contenttion and tune it appropriately.

Attached is a document (note from metalink) on how to analyze ORA-04031 ERROR AND SHAREDPOOL FRAGMENTATION.


IA