Machine IO slowing over time

[Aaron D. Johnson]

Grant Johnson writes:
> I have a machine that the IO throughput is getting slower steadily
> over time.  the hdparm -t shows 180MB/sec on all of the drives which
> is not impressive, but isn't terrible for spinning rust.  I see
> nothing failing in the SMART data.  RAID resync is not happening
> right now.
>
> I am running LVM on top of 2 RAID1 pairs.
>
> What else should I be checking?

I'd start with iotop for which there are at least 2 implementations:
http://guichaz.free.fr/iotop/ and https://github.com/Tomas-M/iotop
It may well be packaged in your OS, too.

iostat and sar (both from http://sebastien.godard.pagesperso-orange.fr/)
are also be worth looking into.

Interpreting numbers from the above tools takes practice.  But they
are good places to start.

- Aaron