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RE: Filesystem for Linux production database server?

From: Matthew Zito <>
Date: Wed, 02 Jul 2003 10:59:12 -0700
Message-ID: <>

Reiserfs' biggest strength is in its ability to deal with directories with huge numbers of files in a very speedy fashion. Obviously, for oracle this is less relevant.

As far as the max-readahead option, I don't understand the specific relevance to fibre-attached storage. I would imagine, though admittedly I no longer have large storage arrays to play with, that setting readahead to be higher could damage performance against arrays with "intelligent" caching algorithms. Having the OS handle read-ahead rather than the array will likely fool the array into thinking that the i/o patterns are more sequential than they are. This will cause them to pre-allocate cache regions and pre-fetch more tracks off disk, which could adversely impact performance.

Totally separate from that, Redhat strongly advises _against_ tuning that parameter.

I happen to be doing I/O testing right now anyway, so maybe I'll gen up some workloads on different filesystems and go nuts.


Matthew Zito
GridApp Systems
Cell: 646-220-3551
Phone: 212-358-8211 x 359

> -----Original Message-----
> Behalf Of Craig I. Hagan
> Sent: Wednesday, July 02, 2003 4:11 AM
> To: Multiple recipients of list ORACLE-L
> Subject: Re: Filesystem for Linux production database server?
> > Linux file systems usually do not support direct I/O (bypassing the
> > buffer cache), which means that you're going to have double caching
> > with almost
> This is no longer the case. Look at the O_DIRECT open option,
> which can be used with oracle. Make sure that your
> distribution has support for it.
> One other thing: if you are using fibre attached storage and
> are *not* using async io, then put some usefully large value
> into /proc/sys/vm/max-readahead, remember it is power of 2
> minus one, so youd want to look at values like 255, 511, and 1023.
> > As for availability, you'll have to go with some RAID
> controller and
> > standby
> > database or RAC. In case of RAC, your choice of file
> systems is clear (OCFS).
> > Whatever you do, do not configure your RAID as RAID-5 but
> RAID 1+0 (BARF).
> what he said, save that i like raid10.
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Received on Wed Jul 02 2003 - 12:59:12 CDT

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