[CentOS] measuring iops on linux - numbers make sense?

Fri Dec 4 22:12:28 UTC 2009
nate <centos at linuxpowered.net>

Amos Shapira wrote:
> Hello,
> When approaching hosting providers for services, the first question
> many of them asked us was about the amount of IOPS the disk system
> should support.

Really depends on what level your measuring IOPS. Most frequently
IOPS means disk IOPS not cache IOPS.

Your typical enterprise SATA disk is built to handle roughly 90
IOPS, your typical enterprise 10k SAS/FC disk 180 IOPS, your
typical enterprise 15k SAS/FC disk 250 IOPS.

The actual number varies depending on the I/O size, for example
if your workload(or controller) sends large I/Os to the disk the
amount of IOPS the disk will do will drop(I've seen SATA disks
on my enterprise storage system peg out at 35 IOPS for example)

Amount of IOPS also is greatly influenced by RAID type and
% of read/write workload.

If your application is pretty simple then go build a system
config that can run it, and take the raw IOPS of the disks
and send it to the hosting provider.

Myself I measure IOPS on my storage array, I trust the numbers
there much more than the OS. I can get per volume, per disk,
and per-host statistics.