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Re: Server Hardware Configuration

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Mario Splivalo <mario(dot)splivalo(at)mobart(dot)hr>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: Server Hardware Configuration
Date: 2005-11-21 16:59:24
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-admin
On Mon, Nov 21, 2005 at 10:34:36AM +0100, Mario Splivalo wrote:
> > RAID5 generally doesn't make for a fast database. The problem is that
> > there is a huge amount of overhead everytime you go to write something
> > out to a RAID5 array. With careful tuning of the background writer you
> > might be able to avoid some of that penalty, though your read
> > performance will likely still be affected by the write overhead.
> RAID5 was not ment to improve performance, but to minimize disaster and
> downtime when your hard disk dies. We're using RAID5 with postgres. In
> the last 3 years we changed 5 disks, but the system downtime was zero
> minutes.

And the same would have been true with RAID10. In fact, RAID10 is more
reliable than RAID5; depending on what drives fail it's possible to lose
up to half of a RAID10 array without any data loss. If you ever lose
more than 2 drives at once with RAID5, your data is gone.
Jim C. Nasby, Sr. Engineering Consultant      jnasby(at)pervasive(dot)com
Pervasive Software    work: 512-231-6117
vcard:       cell: 512-569-9461

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