Re: RAID-1 and disk I/O
Hi.
On Sat, Jul 17, 2021 at 02:03:15PM -0700, David Christensen wrote:
> > But much more noticable is the difference of data reads of the two
> > disks, i.e. 55 GB and 27 GB, i.e. roughly twice as much data is read
> > from /dev/sdb compared to /dev/sda. Trying to figure out the reason
> > for this, dmesg didn't give me anything
>
> Getting meaningful information from system monitoring tools is
> non-trivial. Perhaps 'iostat 600' concurrent with a run of bonnie++.
> Or, 'iostat 3600 24' during normal operations. Or, 'iostat' dumped to
> a time-stamped output file run once an hour by a cron job.
iostat belongs to sysstat package.
sysstat provides sar, which, by default, gathers every detail of the
host resource utilization and a little more once per 10 minutes.
There's little need for the kludges you're describing for one can simply
invoke "sar -pd -f /var/log/sysstat/sa...".
Reco
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