Re: Oracle 11.2 on AIX 7.1 JFS2 mount options

On 2016/12/21 13:46, Martin Klier - Performing Databases GmbH wrote:

> I am calling out for Oracle-on-AIX knowledge/experience bearers, and have a question whether setting the "cio" mount option for datafiles, redo logs and control files for DB version 11.2.0.4 on AIX 7.1 with JFS2 or not.
>
> We are using filesystemio_options=setall for this customer setup.
>
> ...
>
> Simple question:
> I have massively concurrent IO on datafiles (usual read/write activity) and redo logs (streams capture) with many (so far unavoidable) "db file sequential read" and "log file sync" waits.
> Should I activate JFS2 mount option -cio for my data files and redo log file systems?

Short answer: use "filesystemio_options=setall" in Oracle 11.2 and do _not_ use the "cio" mount option on JFS2 mountpoints in AIX 7.x.

You can verify that CIO is being used by tracing sessions on a _TEST_ Oracle instance. A google and MOS 1478924.1 can help you with that. Please test! When you run into issues in the future, you can prove that it's not a lack of CIO that is the problem.

Also see the "AIX Concurrent I/O for Oracle archive logs" thread on this list from 2010.

"log file sync" waits do not necessarily come from slow disk resulting from suboptimal IO setup. I have very low latency writes, but have log file sync waits due to over-committing, for (a poor) example.

GL!

Rich

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