How to add more physical disks to a mirror vdev (to increase redundancy)?

Question

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?

ewwhite · Accepted Answer · 2017-04-13 15:45:33Z

11

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

answered Apr 13, 2017 at 15:29

ewwhite

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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

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