RE: linux DBA's: O_Direct

>>>>I run database backups to an ext3 filesystem, using both
>>>rman and regular hotbackups on different servers. Linux uses
>>>all available ram to cache the writes to ext3, which can

If this is RMAN, why isn't oracle using O_DIRECT for the ext3 target?

10gR2 will do open(,O_DIRECT,) on ext3 if you set filesystemio_options=directIO.
I would recommend doing that, but then I'd also recommend a filesystem where you can put any thing you please in there - without the worry of landmines to step on...none of this "Uh, I think I'll put some goodies in ocfs filesystem, but then I have to put these other goodies in ext3 so my system doesn't blow up"

Kevin Closson
Chief Architect, Database Solutions
PolyServe
www.polyserve.com

>>>reduce free memory to 10-20MB (the box has 12GB) - this is
>>>how it is supposed to work. Sometimes the kernel is unable
>>>to allocate ram for new processes when it drop to this level
>>>and causes errors. It seems to me that filesystem block
>>>caching is unsuitable for a database server - it is not an
>>>issue for OCFS, only for backups to ext3.
>>>>
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