| From: | Greg Smith <greg(at)2ndquadrant(dot)com> |
|---|---|
| To: | Yeb Havinga <yebhavinga(at)gmail(dot)com> |
| Cc: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Testing Sandforce SSD |
| Date: | 2010-08-03 14:02:19 |
| Message-ID: | 4C58216B.7050401@2ndquadrant.com |
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| Thread: | |
| Lists: | pgsql-performance |
Yeb Havinga wrote:
> Small IO size: 4 KB
> Maximum Small IOPS=86883 @ Small=8 and Large=0
>
> Small IO size: 8 KB
> Maximum Small IOPS=48798 @ Small=11 and Large=0
Conclusion: you can write 4KB blocks almost twice as fast as 8KB ones.
This is a useful observation about the effectiveness of the write cache
on the unit, but not really a surprise. On ideal hardware performance
should double if you halve the write size. I already wagered the
difference in pgbench results is caused by the same math.
--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.us
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