From: Andy Colson <andy@squeakycode.net>
To: Igor Chudov <ichudov@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Postgres for a "data warehouse", 5-10 TB
Date: Sun, 11 Sep 2011 09:36:25 -0500
Message-ID: <4E6CC769.10604@squeakycode.net> (raw)
In-Reply-To: <CAMhtkAY2GvGiTz23V10Bev-ibrPWE7GowocT3KeWKm1EoED7WA@mail.gmail.com>
References: <CAMhtkAbK7saRO_Tayb1nS3YLWN=Wns=Ci47qs-3YbX0T2+hkpA@mail.gmail.com>
<CAOR=d=0zmw-EGRJyYmwCTxR5g6osbFLS5i-3kzjG05j7S=1JaA@mail.gmail.com>
<CAMhtkAah2c4XfSec=OtgL1V51wpD=jygbZnBVBRYCV02MscebQ@mail.gmail.com>
<CAGTBQpYa+VUXtKZtUDLSosboSMgUEOCd_dkmCPA=4HkjHw2r2g@mail.gmail.com>
<CAMhtkAY2GvGiTz23V10Bev-ibrPWE7GowocT3KeWKm1EoED7WA@mail.gmail.com>
On 09/11/2011 09:21 AM, Igor Chudov wrote:
>
>
> On Sun, Sep 11, 2011 at 9:16 AM, Claudio Freire <klaussfreire@gmail.com <mailto:klaussfreire@gmail.com>> wrote:
>
> On Sun, Sep 11, 2011 at 3:59 PM, Igor Chudov <ichudov@gmail.com <mailto:ichudov@gmail.com>> wrote:
> > Well, right now, my server has twelve 7,200 RPM 2TB hard drives in a RAID-6
> > configuration.
> > They are managed by a 3WARE 9750 RAID CARD.
> >
> > I would say that I am not very concerned with linear relationship of read
> > speed to disk speed. If that stuff is somewhat slow, it is OK with me.
>
> With Raid 6 you'll have abysmal performance on write operations.
> In data warehousing, there's lots of writes to temporary files, for
> sorting and stuff like that.
>
> You should either migrate to raid 10, or set up a separate array for
> temporary files, perhaps raid 0.
>
>
> Thanks. I will rebuild the RAID array early next week and I will see if I have a Raid 10 option with that card.
>
> Quantitatively, what would you say is the write speed difference between RAID 10 and RAID 6?
>
Note that using RAID 10, while faster, cuts your usable space in half. 12 2TB drives in raid 10 == 6 drives * 2TB == 12 TB total space. That's not big enough, is it?
-Andy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: andy@squeakycode.net, ichudov@gmail.com
Subject: Re: Postgres for a "data warehouse", 5-10 TB
In-Reply-To: <4E6CC769.10604@squeakycode.net>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox