Re: NFS vs. md raid

"Stephen John Smoogen" <[email protected]>
Newsgroups gmane.linux.redhat.release.taroon.general
Message-ID <[email protected]>
On 6/8/06, Christopher McCrory <[email protected]> wrote:
> Hello...
>
>   speaking of NFS...
>
>   I've continually had slow write performance ( specifically file
> creation) with RHEL3 when the NFS server filesystem is a software raid
> device.  THe same thing happens with RHEL4.  When using a single drive
> as an export, performance is fast.  So far the only option I have found
> that helps is exporting with the 'async' option.  All clients are also
> RHEL


Well a lot of questions can affect this:

1) What kind of disk controller
2) What kind of disk drives?
3) What kind of RAID?
4) What kind of NFS?

>
> example:
> time tar -xzf lots.of.files.tar.gz
>
> local drive:
> real    0m6.053s
> user    0m2.210s
> sys     0m1.180s
>
> nfs with async (insane)
> real    0m6.492s
> user    0m2.150s
> sys     0m1.140s
>
> nfs with sync  (sane)
> real    1m52.756s
> user    0m2.430s
> sys     0m1.290s
>
>
> 6 seconds vs. 120 seconds.  Ouch
>
> Any ideas?
>
>
> --
> Christopher McCrory
>  "The guy that keeps the servers running"
>
> [email protected]
>  http://www.pricegrabber.com
>
> Let's face it, there's no Hollow Earth, no robots, and
> no 'mute rays.' And even if there were, waxed paper is
> no defense.  I tried it.  Only tinfoil works.
>
> --
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>


-- 
Stephen J Smoogen.
CSIRT/Linux System Administrator

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