Re: dell versus hp

Le Thursday 08 November 2007 19:22:48 Scott Marlowe, vous avez écrit :
> On Nov 8, 2007 10:43 AM, Vivek Khera <khera(at)kcilink(dot)com> wrote:
> > On Nov 6, 2007, at 1:10 PM, Greg Smith wrote:
> > > elsewhere. But once you have enough disks in an array to spread all
> > > the load over that itself may improve write throughput enough to
> > > still be a net improvement.
> >
> > This has been my expeience with 14+ disks in an array (both RAID10 and
> > RAID5). The difference is barely noticeable.
>
> Mine too.

May we conclude from this that mixing WAL and data onto the same array is a
good idea starting at 14 spindles?

The Dell 2900 5U machine has 10 spindles max, that would make 2 for the OS
(raid1) and 8 for mixing WAL and data... not enough to benefit from the move,
or still to test?

> I would suggest though, that by the time you get to 14
> disks, you switch from RAID-5 to RAID-6 so you have double redundancy.
> Performance of a degraded array is better in RAID6 than RAID5, and
> you can run your rebuilds much slower since you're still redundant.

Is raid6 better than raid10 in term of overall performances, or a better cut
when you need capacity more than throughput?

Thanks for sharing the knowlegde, regards,
--
dim