Re: Dell Hardware Recommendations

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(at)decibel(dot)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(at)decibel(dot)org
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)