Checking disk activity with ZFS – iostat

Pretty neat little command that I wasn’t aware before, but quick check of the manpage would bring it to my attention. :-)

To check current disk activity stats on your zpool you can use:

zpool iostat -v POOLNAME

You can of course omit pool name, without it it’ll show statistics for all pools.

Command output example:

$ zpool iostat -v
               capacity     operations    bandwidth
pool        alloc   free   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
storage      838G   554G      1     40  54.4K   573K
  mirror     838G   554G      1     40  54.4K   573K
    sdb         -      -      0     12  28.0K   585K
    sdc         -      -      0     12  29.1K   585K
----------  -----  -----  -----  -----  -----  -----

Without -v switch you would get per-pool statistics, removing information about mirrors and per-disk statistics, so only pool statistics:

$ zpool iostat
               capacity     operations    bandwidth
pool        alloc   free   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
storage      838G   554G      1     41  54.5K   573K