RE: Software vs Hardware RAID 10?
> -----Original Message-----
> From: Dave Ewart [mailto:davee@ceu.ox.ac.uk]
> Sent: 30 August 2007 16:55
> To: debian-amd64@lists.debian.org
> Subject: Re: Software vs Hardware RAID 10?
>
> On Thursday, 30.08.2007 at 10:37 +0200, Goswin von Brederlow wrote:
>
> > > [RAID 6]
> >
> > If you write a single block then you have to read the 2
> parity blocks
> > for the stripe, update them and write 3 blocks. So you have 5 times
> > the traffic on the bus. For anything doing single block
> writes this is
> > quite the killer. I would imagine a database like oracle to
> just die
> > with software raid6.
>
> *nods* I believe most database 'vendors' recommend RAID-10,
> and specifically to avoid any of the parity-based RAIDs, such
> as RAID-5 and RAID-6. Presumably for exactly the reasons
> you've outlined. For example, see
> http://edoceo.com/liber/db-postgresql-performance.php
No, the main reasons for recommending against RAID-5/6 are
not connected to performance during normal operation.
Choosing the correct storage system is never primarily about
speed, the first considerations are always: reliability,
fault-tolerance, disaster-recovery, and fool-proof setup.
The Battle Against Any Raid Five initiative provides much
more information on why RAID-5 and RAID-6 should be avoided
for production servers:
<http://www.miracleas.com/BAARF/BAARF2.html?30,42>
The above site should be required reading for anyone with
critical data.
Paul
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