[libvirt-users] Performance tuning questions for mail server

[Emmanuel Noobadmin]

On 10/7/11, Alex <mysqlstudent at gmail.com> wrote:
> Can I also ask how you measured performance and the effect any changes
> you made may have had on the system?
>
> iotop seems very general. Perhaps sar? Ideas for graphing its output?

Well for that situation, people were screaming at me so I didn't
really measured things empirically. It was just throwing one possible
fix after another, while watching the system load iowait % go down
until things were smooth again.

Another key thing is having sufficient memory for the VM but I don't
think that's your problem since you have 8GB on it. Then again, it
would really depend on how much mails you are handling.

But if you have time for measurement, as well as can afford the
time/impact, you can try iozone which produces detailed stats and
includes graphing functionality IIRC.

The other tool I use is iostat.

Although I'm also thinking of writing a script that more closely mimic
the kind of loads on my typical server i.e. many small email files
written + some reads and random updates to a single large file (e.g.
log file, user db).