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@xxxxxxxxx> wrote:
Francisco Reyes wrote: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).
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.
regards,
Yeb Havinga
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