Can more physical drives be added to mirror vdevs after a zpool has been created?

For example, if a zpool is created using:

zpool create test_pool mirror /dev/sd0 /dev/sd1 mirror /dev/sd2 /dev/sd3

Can more drives be added to the vdevs to increase their redundancy? That is, can the number of mirrored drives be increased from 1 to 2?


1 Answer 1


Yes. Yes they can.

Something like the following would add to an existing mirror and yield a triple-mirror, given the example above:

zpool attach test_pool /dev/sd0 /dev/sd4
zpool attach test_pool /dev/sd2 /dev/sd5
  • 2
    To clarify, I meant to add drives to increase redundancy so that the zpool created by zpool create test_pool mirror /dev/sd0 /dev/sd1 mirror /dev/sd2 /dev/sd3 would be equivalent to zpool create test_pool mirror /dev/sd0 /dev/sd1 /dev/sd4 mirror /dev/sd2 /dev/sd3 /dev/sd5 after the drives are added, would those commands do that?
    – Greg
    Apr 13, 2017 at 15:38
  • 2
    Yes, that's what I posted.
    – ewwhite
    Apr 13, 2017 at 15:44
  • 2
    @Dave This also works if you have basic vdevs (single disks), they can be converted to mirrors (attach) and the mirrors can be degraded back to basic vdevs (detach). See docs.oracle.com/cd/E19253-01/819-5461/6n7ht6qvl/index.html for more examples.
    – user121391
    Apr 18, 2017 at 12:32

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .