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[linux-lvm] Re: lvm2 performance data with linux-2.6



markw osdl org wrote:
I've started collecting various data (including oprofile) using our
DBT-2 (OLTP) workload with lvm2 on linux 2.6.2 and 2.6.3 on ia32 and
ia64 platforms:
	http://developer.osdl.org/markw/lvm2/

So far I've only varied the stripe width with lvm, from 8 KB to 512 KB,
for PostgreSQL that is using 8 KB sized blocks with ext2.  It appears
that a stripe width of 16 KB through 128KB on the ia64 system gives the
best throughput for the DBT-2 workload on a volume that should be doing
mostly sequential writes.

I'm going to run through more tests varying the block size that
PostgreSQL uses, but I wanted to share what I had so far in case there
were other suggestions or recommendations.

Here's one thought: look at the i/o rates on individual drives using each stripe size. You *might* see that one size does far fewer seeks than others, which is a secondary thing to optimize after throughput IMHO.

If you don't have a tool for this I can send you the latest diorate which does stuff like this, io rate perdrive or per partition, something I occasionally find revealing.

-bill



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