CIO filesystem impact on Oracle SGA

[Former Member]

Hi all,

We have recently upgrade our database to Oracle 10G but we have not activated CIO filesystem option (AIX 5.3).

We have a project to reorganize our filesystem to be able to activate concurrent I/O, but I some question about the impact on the Oracle SGA:

- After CIO activation I should extend my Oracle SGA?

- If yes, how can I estimate the new SGA size?

other question is :

- Is there other AIX parameters that should be changed?

Thanks for your replies.

Sam

[stefan_koehler · Accepted solution]

Hello Sam,

> - After CIO activation I should extend my Oracle SGA?

> - If yes, how can I estimate the new SGA size?

No, you don't have to extend your buffer cache. If you think about the file system cache (numperm) then you maybe have a very little impact on not frequently used blocks .. but you shouldn't think about that.

Btw. just as a little hint .. if you are using Oracle 10g with file system option SETALL on JFS2 file systems .. you are already using CIO )

Regards

Stefan