Re: About AIX configuration for Oracle
Date: Tue, 20 Oct 2009 20:49:21 +1000
There are no "fix all" magic settings. And a lot of the papers available from IBM may be slightly out of date: AIX keeps evolving and recommended processes do indeed change. On any papers you download, check which release(s) are they applicable to.
http://dbasrus.blogspot.com/2009/06/size-sometimes-does-matter.html I've put together some of the things that worked really well for us. Namely:
- setting largepages AND using them from Oracle guarantees they won't get paged out or swapped out. Other things may, instead. And you'll have less memory for file system buffers so if you happen to do a lot of buffered I/O, that will suffer.
Please read the whole post and the comments: there are good hints there as well and there is a link to the latest version of memory tuning papers. Pay particular attention to lrufilerepage setting.
Also please note that how Oracle handles Concurrent IO changes from patch level to patch level: you must check what yours is doing with truss. For example: CIO doesn't work with 10.2.0.4 until you apply a patch. Again: please read the comments as well as the blog post.
-- Cheers Nuno Souto in sunny Sydney, Australia dbvision_at_iinet.net.au Gil Cota wrote,on my timestamp of 20/10/2009 8:38 AM:Received on Tue Oct 20 2009 - 05:49:21 CDT
> Iíve an Oracle RAC Database 10.2.0.4 using ASM on AIX 6.1, my server got
> 64GB RAM ,
> And Oracle is using just 20GB for the SGA and another 10GB for the 1000
> user connections,
> My question is the following , Iím seeing the memory on the server at
> 99.3% occupied I know this is because of the maxperm% and minperm%
> parameters ,
> But because Iíve got a load storm, several connection to Oracle (about a
> 800 connection) the server started swapping and did a reboot because the
> CRS didnít have cpu to schedule the heartbeat,
> So my question is why does AIX do swapping when I have like 32gb of RAM
> on the filesystem cache ?
> The other question is does anyone have recommended kernel parameterís
> (maxperm% , minperm% , etc) for this kind of configuration ? because
> Oracle documentation and metalink are quite different in terms of
> recommendationís Ö.