Re: 10K vs 15k rpm for analytics - Mailing list pgsql-performance

From Dave Crooke
Subject Re: 10K vs 15k rpm for analytics
Date
Msg-id ca24673e1003021305p7014202dj3c5a2ff575ce4e83@mail.gmail.com
Whole thread Raw
In response to Re: 10K vs 15k rpm for analytics  (Yeb Havinga <yebhavinga@gmail.com>)
List pgsql-performance
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 <yebhavinga@gmail.com> 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


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