Re: raid array seek performance

On 09/13/2011 03:13 PM, Samuel Gendler wrote:
> Bonnie++ delivered the expected huge throughput for sequential read
> and write.  It seems in line with other benchmarks I found online.
>  However, we are only seeing 180 seeks/sec, but seems quite low.

I wouldn't worry about that if the sequential rates are good.  The
bonnie++ seeks test has been giving me increasingly useless results
recently on modern hardware.  And bonnie++ 1.96 continues to give me
enough weird values that I'm still using 1.03e as my standard version.

If you want to get a useful measurement of seeks/second, setup
pgbench-tools with a SELECT-only test, and create a database that's 2 to
4X as big as RAM.  The TPS result you get from that is a much more
useful number for real-world seeks than this.

I'm working on a tool to directly benchmark seek performance in a way
that's useful for what people really want to know nowadays.  That's
going live to the world at the end of the month, at #PgWest:
http://pgwest2011.sched.org/event/875b87d8d237bef3a53ab27ac9c8057c

--
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us