direct IO or cache Io on LINUX server?

[martin campbell]

hi, for Oracle we've found for files that have a high IO rate like temp
tablespaces & redo logs that we get a significant performace improvement
using DirectIO, so we create a directIO slice just for these types of
files.

hth

ta
martin.  

On Fri, 2006-05-12 at 05:09 +0800, mcclnx mcc wrote:
> we have several DELL 6800 with LSI 4e/DC adapter cards
> (128 MB cache) in it.  DELL 6800 run under Redhar AS
> 4.0 and ORACLE 9ir2.  When I configured DELL 6800
> server local disks (Mirror or RAID 5), it  have two
> I/O policy to choice - direct IO and cache IO.
> 
> I doing simple test by copy files between differents
> disk set and found  "direct IO" performance better
> than "cache IO". It is against what I read before.  I
> used to saw documents from SUN and IBM said "large
> disk array cache will improve I/O performance".
> 
> Any one has suggestion FOR ORACLE server which I/O
> policy should I setup?
> 
> Thanks.
> 
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