Re: linux memory: limiting filesystem caching

if you mean that the oracle is swapping it's memory? you can use LOCK_SGA init parameter with the oracle to make it lock the sga in the memory without doing any swap.

you should use lock_sga with rac any way.

This parameter is not working in all platforms, but i think it works with linux.

Regards,
Oded.

On 7/13/05, Teehan, Mark <mark.teehan_at_csfb.com> wrote:
>
> Hi all
> I have several redhat blade clusters running 10.1.0.4 <http://10.1.0.4>RAC on
> 2.4.9-e.43enterprise. All database storage is OCFS, with ext3 for backups,
> home dirs etc. The servers have 12GB of RAM, of which about 2GB is allocated
> to the database, which is fine. Linux, in its wisdom, uses all free memory
> (10GB in this case) for filesystem caching for the non OCFS filesystems
> (since OCFS uses directIO); so every night when I do a backup it swallows up
> all available memory and foolishly sends itself into a swapping frenzy; and
> afterwards it sometimes cannot allocate enough free mem for background
> processes. This seems to be worse on e43; I was on e27 until recently. Does
> anyone know how to control filesystem block caching? Or how to get it to
> de-cache some? For instance, I have noticed that gziping a file, then
> ctrl-C'ing it can free up a chunk of RAM, I assume it de-caches the original
> uncompressed file. But its not enough!
>
> Rgds
> Mark
>
>
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