I'm testing a large ZFS pool at the minute and am documenting the process for replacing a failed drive before our environment moves into production.

I've built the ZFS volume 'diskpool', which is 3 nested vdevs of 20 x 8TB drives. Everything is working fine.

To simulate a disk failure, I've disconnected one of the 8tb drives.

I'm a little worried, because with the drive disconnected, If i run 'zpool status', I'm still showing 'ONLINE' as the state against all of my disks.

The disk controller that all of the devices are connected to has reporting mechanisms in place, and that immediately alerted me to say a disk has either failed or been removed, but ZFS doesn't seem any the wiser.

Can someone shed some light on why it would still report a 'failed' disk as 'ONLINE'?

  • 1
    What OS are you running on? Commented Mar 31, 2016 at 14:41
  • I'm running Centos 7.2
    – John
    Commented Mar 31, 2016 at 14:44
  • 1
    Did you try reading data from the pool?
    – jlliagre
    Commented Mar 31, 2016 at 14:47
  • @ Jilliagre, no I had not sigh. As soon as I did, the status changed. Thank you kindly
    – John
    Commented Mar 31, 2016 at 14:58
  • You're welcome, comment turned into an answer.
    – jlliagre
    Commented Mar 31, 2016 at 15:55

1 Answer 1


The ZFS implementation you use doesn't poll its underlying devices unless there is some activity going on.

Removing a disk from a pool that is not accessed will then remain unnoticed until you access it.

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