> -----Original Message-----
> From: pgsql-performance-owner@postgresql.org
> [mailtogsql-performance-owner@postgresql.org] On Behalf Of
> Vivek Khera
> Sent: 08 December 2005 16:52
> To: Postgresql Performance
> Subject: [PERFORM] opinion on disk speed
>
> I have a choice to make on a RAID enclosure:
>
> 14x 36GB 15kRPM ultra 320 SCSI drives
>
> OR
>
> 12x 72GB 10kRPM ultra 320 SCSI drives
>
> both would be configured into RAID 10 over two SCSI channels using a
> megaraid 320-2x card.
>
> My goal is speed. Either would provide more disk space than I would
> need over the next two years.
>
> The database does a good number of write transactions, and a decent
> number of sequential scans over the whole DB (about 60GB including
> indexes) for large reports.
>
> My only concern is the 10kRPM vs 15kRPM. The advantage of the 10k
> disks is that it would come from the same vendor as the systems to
> which it will be connected, making procurement easier.

15K drives (well, the Seagate Cheetah X15's that I have a lot of at
least) can run very hot compared to the 10K's. Might be worth bearing
(no pun intended) in mind.

Other than that, without knowing the full specs of the drives, you've
got 2 extra spindles and a probably-lower-seek time if you go for the
X15's so that would seem likely to be the faster option.

Regards, Dave


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On Thu, 8 Dec 2005 17:03:27 -0000
"Dave Page" <dpage@vale-housing.co.uk> wrote:

> > -----Original Message-----
> > From: pgsql-performance-owner@postgresql.org
> > [mailtogsql-performance-owner@postgresql.org] On Behalf Of
> > Vivek Khera
>
> > I have a choice to make on a RAID enclosure:
> >
> > 14x 36GB 15kRPM ultra 320 SCSI drives
> >
> > OR
> >
> > 12x 72GB 10kRPM ultra 320 SCSI drives
> >
> > both would be configured into RAID 10 over two SCSI channels using
> > a megaraid 320-2x card.
>
> 15K drives (well, the Seagate Cheetah X15's that I have a lot of at
> least) can run very hot compared to the 10K's. Might be worth bearing
> (no pun intended) in mind.
>
> Other than that, without knowing the full specs of the drives, you've
> got 2 extra spindles and a probably-lower-seek time if you go for the
> X15's so that would seem likely to be the faster option.

I agree, the extra spindles and lower seek times are better if all
you are concerned about is raw speed.

However, that has to be balanced, from an overall perspective, with
the nice single point of ordering/contact/support/warranty of the
one vendor. It's a tough call.

---------------------------------
Frank Wiles <frank@wiles.org>
http://www.wiles.org
---------------------------------


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Frank Wiles wrote:

>
>
> I agree, the extra spindles and lower seek times are better if all
> you are concerned about is raw speed.
>
> However, that has to be balanced, from an overall perspective, with
> the nice single point of ordering/contact/support/warranty of the
> one vendor. It's a tough call.

Well, if your favourite dealer can't supply you with such common
equipment as 15k drives you should consider changing the dealer. They
don't seem to be aware of db hardware reqirements.

Regards,
Andreas


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On Dec 9, 2005, at 10:50 AM, Andreas Pflug wrote:

> Well, if your favourite dealer can't supply you with such common
> equipment as 15k drives you should consider changing the dealer.
> They don't seem to be aware of db hardware reqirements.

Thanks to all for your opinions. I'm definitely sticking with 15k
drives like I've done in the past for all my other servers.

The reason I considered the 10k was because of the simplicity of
ordering from the same vendor. They do offer 15k drives, but at
double the capacity I needed (73GB drives) which would make the cost
way high and overkill for what I need.


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