How to detemine LARGE_POOL_SIZE

[Sharma]

What factor needs to be considerd in detemining LARGE_POOL_SIZE.

I am using RMAN for Backup and Shared Server process (Multi Threaded Architecture).

[stecal]

The two you mentioned: using RMAN for backup and MTS. It is not required, but is recommended if you are using either of the above. If you don't use it, memory for user sessions and RMAN backup is allocated from the shared pool, which in turn may cause fewer SQL statements to be cached.

Default size is zero. Minimum size is 600K. Max size is OS dependent, but will be at least 2GB.

From Oracle8i DBA Bible by Gennick.

[julian]

Originally posted by Sharma
What factor needs to be considerd in detemining LARGE_POOL_SIZE.

I am using RMAN for Backup and Shared Server process (Multi Threaded Architecture).

There is a formula suggested by Oracle:

LARGE_POOL_SIZE = (4 * {RMAN Channels} * {DB_BLOCK_SIZE} * {DB_DIRECT_IO_COUNT} * {Multiplexing Level}) + (4 * {RMAN Channels} * {Tape Buffer Size})

In real life, 20-100M will do the job. I use RMAN and set it to 32M :-)

[pando]

to calculate MTS

get average session uga memory max from all sessions and multiply the number of sessions you think you will have

[Sharma]

As LARGE POOL don't uses LRU algorithm,
What should I be doing to avoid ORA-4031, will Oracle releases memory from LARGE POOL once the session dis connects.
How LARGE POOL space is released once the RMAN backup is over.
What should be the value LARGE_POOL_MIN_ALLOC, as I read somewhere, each active session needs around 300KB, should I set it close to this no.

Please advise.
Thanks!