From: Decibel! <decibel@decibel.org>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Dell Hardware Recommendations
Date: Thu, 9 Aug 2007 23:58:58 -0500
Message-ID: <20070810045857.GL20424@nasby.net> (raw)
In-Reply-To: <dcc563d10708091858u4f4a3cf9s902cdc9fcd28032a@mail.gmail.com>
References: <46BB6F3D.6090608@gmail.com>
<b42b73150708091450t448e3fa0nc778ab87d639603@mail.gmail.com>
<20070809220502.GE20424@nasby.net>
<dcc563d10708091529n448affd5nf083f90b99d42289@mail.gmail.com>
<20070809224138.GI20424@decibel.org>
<dcc563d10708091858u4f4a3cf9s902cdc9fcd28032a@mail.gmail.com>
On Thu, Aug 09, 2007 at 08:58:19PM -0500, Scott Marlowe wrote:
> > On Thu, Aug 09, 2007 at 05:29:18PM -0500, Scott Marlowe wrote:
> > > On 8/9/07, Decibel! <decibel@decibel.org> wrote:
> > >
> > > > Also, a good RAID controller can spread reads out across both drives in
> > > > each mirror on a RAID10. Though, there is an argument for not doing
> > > > that... it makes it much less likely that both drives in a mirror will
> > > > fail close enough to each other that you'd lose that chunk of data.
> > >
> > > I'd think that kind of failure mode is pretty uncommon, unless you're
> > > in an environment where physical shocks are common. which is not a
> > > typical database environment. (tell that to the guys writing a db for
> > > a modern tank fire control system though :) )
You'd be surprised. I've seen more than one case of a bunch of drives
failing within a month, because they were all bought at the same time.
> > > > while with RAID10 you can
> > > > potentially lose half the array without losing any data.
> > >
> > > Yes, but the RIGHT two drives can kill EITHER RAID 5 or RAID10.
Sure, but the odds of that with RAID5 are 100%, while they're much less
in a RAID10.
> > > While I agree with Merlin that for OLTP a faster drive is a must, for
> > > OLAP, more drives is often the real key. The high aggregate bandwidth
> > > of a large array of SATA drives is an amazing thing to watch when
> > > running a reporting server with otherwise unimpressive specs.
True. In this case, the OP will probably want to have one array for the
OLTP stuff and one for the OLAP stuff.
--
Decibel!, aka Jim Nasby decibel@decibel.org
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
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To: pgsql-performance@postgresql.org
Cc: decibel@decibel.org, scott.marlowe@gmail.com
Subject: Re: Dell Hardware Recommendations
In-Reply-To: <20070810045857.GL20424@nasby.net>
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