Dear Srs,

We're experimenting low perfomance issues with Open-iSCSI with Linux 2.6.18
and using CFQ as I/O scheduler. It happens in all servers running Virtuozzo
with near about 10 virtual machines per node. vmstat reports +30-40% for
I/O wait.. and load average is very high.

Changing I/O scheduler from iSCSI device from "cfq" to "noop" performance
is OK, as expected -5% of I/O wait.

It's curious, when changing from "cfq" to "noop" there are less reads that
when using cfq!! I have measured using dstat, vmstat, etc.. and always
occurs the same :-/

What's the recomended I/O scheduler for an iSCSI devices?

And... which tool is recomended to benchmark iSCSI devices, fio, bonnie++,
etc..? thanks!


Santi Saez

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