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I have a storage pool aptly called storage
with two disks in it. Originally, I wanted to add the second disk as a mirror but did the ZFS newbie mistake of using zpool add storage <device>
instead of zpool attach storage <device>
.
Every attempt to remove
or detach
the second device from the pool fails, because ZFS complains about not having redundant drives. After reading into it, I understand the issue and why this is. However, I wasn't able to find a solution how to either remove the drive to re-attach it or simply convert the whole pool to mirrored instead of striped. I'm also kind of puzzled by the fact there seems to be no straight-forward way to do it.
Is there a way to achieve this short of destroying and recreating the pool? I'd rather not need to buy another 4TB drive and copy all that data over.
Regarding the raidz2 advice: It is true that you can live with the failure of any two disks, but your resilvering times will be slower (all disks have to be read completely instead of only the affected mirror) which also increases the chance of another disk dying in the resilver window, your performance will be worse (especially random reads, and this gets worse as you expand your pool), and finally, your pool expansion now needs four instead of two drives if you want symmetrical layout. You get all the downsides of parity raid with none of the space improvements - I would stick with mirrors. – user121391 – 2016-07-19T07:27:53.697