Re: How to allocate 8 disks

Matthew wrote:
> On Sat, 1 Mar 2008, Craig James wrote:
>> Right, I do understand that, but reliability is not a top priority in
>> this system. The database will be replicated, and can be reproduced
>> from the raw data.
>
> So what you're saying is:
>
> 1. Reliability is not important.
> 2. There's zero write traffic once the database is set up.
>
> If this is true, then RAID-0 is the way to go. I think Greg's options
> are good. Either:
>
> 2 discs RAID 1: OS
> 6 discs RAID 0: database + WAL
>
> which is what we're using here (except with more discs), or:
>
> 8 discs RAID 10: everything

Has anybody been able to prove to themselves that RAID 0 vs RAID 1+0 is
faster for these sorts of loads? My understanding is that RAID 1+0 *can*
reduce latency for reads, but that it relies on random access, whereas
RAID 0 performs best for sequential scans? Does PostgreSQL ever do
enough random access to make RAID 1+0 shine?

Curious.

Thanks,
mark

--
Mark Mielke <mark(at)mielke(dot)cc>