Received: from maia.hub.org (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id DB0AF6333E7 for ; Tue, 2 Mar 2010 17:05:19 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 43529-10 for ; Tue, 2 Mar 2010 21:05:09 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-wy0-f174.google.com (mail-wy0-f174.google.com [74.125.82.174]) by mail.postgresql.org (Postfix) with ESMTP id 8D7D1632D02 for ; Tue, 2 Mar 2010 17:05:08 -0400 (AST) Received: by wya21 with SMTP id 21so374275wya.19 for ; Tue, 02 Mar 2010 13:05:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type; bh=BPWGthsAc6llisyfvUVe5I3EfFuyV2tUxcy7afMd5JA=; b=GLHiKsjKKJADYXj5xEoufYS+EyJWihCdq+L4M3NgzJ6OKu80hmTwh3IsR+Yf/G2hiV igx/l3uAedTaoMLZPzjxTtYovRCN5ERnEBHRCGlA7jHuw7XT3U729ESLRZUGCpN5xZvp DkwUQLtVTQQhhKy99Y1MCIG2jKEUZPSaXKo6Y= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=GfyRJB8qegWhCz7J56pKBKI7G6OZvyh/igF8d/m2sHpkAmYtI7AqFOB9bUxfpi3wX3 PPbY5+I2cU/TLzUDLL8TIREqZeQIgVsGjVIi6eM60abSmUp+boJE1qcKyY9h7wJbywaf cocm3w/ZPtAbA+9V6m0xZGGLzNsvb/Mx4l+4I= MIME-Version: 1.0 Received: by 10.216.86.210 with SMTP id w60mr4453960wee.48.1267563907108; Tue, 02 Mar 2010 13:05:07 -0800 (PST) In-Reply-To: <4B8D7A6C.3010304@gmail.com> References: <4B8D7A6C.3010304@gmail.com> Date: Tue, 2 Mar 2010 15:05:07 -0600 Message-ID: Subject: Re: 10K vs 15k rpm for analytics From: Dave Crooke To: Yeb Havinga Cc: Francisco Reyes , Pgsql performance Content-Type: multipart/alternative; boundary=0016e6d99d0369d0de0480d7b841 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-0.739 tagged_above=-10 required=5 tests=BAYES_20=-0.74, HTML_MESSAGE=0.001 X-Spam-Level: X-Archive-Number: 201003/26 X-Sequence-Number: 37851 --0016e6d99d0369d0de0480d7b841 Content-Type: text/plain; charset=ISO-8859-1 Seconded .... these days even a single 5400rpm SATA drive can muster almost 100MB/sec on a sequential read. The benefit of 15K rpm drives is seen when you have a lot of small, random accesses from a working set that is too big to cache .... the extra rotational speed translates to an average reduction of about 1ms on a random seek and read from the media. Cheers Dave On Tue, Mar 2, 2010 at 2:51 PM, Yeb Havinga wrote: > Francisco Reyes wrote: > >> Anyone has any experience doing analytics with postgres. In particular if >> 10K rpm drives are good enough vs using 15K rpm, over 24 drives. Price >> difference is $3,000. >> >> Rarely ever have more than 2 or 3 connections to the machine. >> >> So far from what I have seen throughput is more important than TPS for the >> queries we do. Usually we end up doing sequential scans to do >> summaries/aggregates. >> >> With 24 drives it'll probably be the controller that is the limiting > factor of bandwidth. Our HP SAN controller with 28 15K drives delivers > 170MB/s at maximum with raid 0 and about 155MB/s with raid 1+0. So I'd go > for the 10K drives and put the saved money towards the controller (or maybe > more than one controller). > > regards, > Yeb Havinga > > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance > --0016e6d99d0369d0de0480d7b841 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Seconded .... these days even a single 5400rpm SATA drive can muster almost= 100MB/sec on a sequential read.

The benefit of 15K rpm drives is se= en when you have a lot of small, random accesses from a working set that is= too big to cache .... the extra rotational speed translates to an average = reduction of about 1ms on a random seek and read from the media.

Cheers
Dave

On Tue, Mar 2, 2010 at= 2:51 PM, Yeb Havinga <yebhavinga@gmail.com> wrote:
Francisco Reyes wrote:
Anyone has any experience doing analytics with postgres. In particular if 1= 0K rpm drives are good enough vs using 15K rpm, over 24 drives. Price diffe= rence is $3,000.

Rarely ever have more than 2 or 3 connections to the machine.

So far from what I have seen throughput is more important than TPS for the = queries we do. Usually we end up doing sequential scans to do summaries/agg= regates.

With 24 drives it'll probably be the controller that is the limiting fa= ctor of bandwidth. Our HP SAN controller with 28 15K drives delivers 170MB/= s at maximum with raid 0 and about 155MB/s with raid 1+0. So I'd go for= the 10K drives and put the saved money towards the controller (or maybe mo= re than one controller).

regards,
Yeb Havinga


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