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@xxxxxxxxxxx> 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@xxxxxxxxxxx EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
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