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Removing a cache disk from a ZFS pool

Featured Replies

Good morning, I'd like to disconnect the NVMe drive that serves as a cache for the ZFS pool:


pool: zfs state: ONLINE scan: scrub repaired 0B in 14:11:27 with 0 errors on Wed Jul 1 13:11:28 2026 config: NAME STATE READ WRITE CKSUM zfs ONLINE 0 0 0

raidz2-0 ONLINE 0 0 0

/dev/sdf1 ONLINE 0 0 0

/dev/sdg1 ONLINE 0 0 0

/dev/sdh1 ONLINE 0 0 0

/dev/sdi1 ONLINE 0 0 0

/dev/sdj1 ONLINE 0 0 0

/dev/sdk1 ONLINE 0 0 0

/dev/sda1 ONLINE 0 0 0

/dev/sdb1 ONLINE 0 0 0

/dev/sdc1 ONLINE 0 0 0

/dev/sdd1 ONLINE 0 0 0

cache /dev/nvme0n1p1 ONLINE 0 0 0 errors: No known data errors

Can you tell me how to do this? After stopping the pool and trying to detach the disk, I get a "missing" message:

image.png

Ultimately, I wanted to use the drive as a bootable drive for Unraid.

Edited by Kulis

Solved by JorgeB

  • Author

@JorgeB Should I do this on the drives that are currently running, or should I stop them?

Edited by Kulis

  • Community Expert
  • Solution

The removal should be done with the array running, since the pool must be imported.

  • Author

Your instructions work!

Now the final step is to reimport the pool without that subpool, to do that:

 

  • stop the array

  • on main, click on the first device for that pool and then "remove pool"

  • back on main, create a new pool with the same name and the new number of slots

  • assign the remaining pool device(s), it can be in any order, they will be sorted at array start

  • leave the filesystem set to auto

  • start the array to import the pool

  • Community Expert
1 hour ago, Kulis said:

Your instructions work!

Now the final step is to reimport the pool without that subpool, to do that:

 

  • stop the array

  • on main, click on the first device for that pool and then "remove pool"

  • back on main, create a new pool with the same name and the new number of slots

  • assign the remaining pool device(s), it can be in any order, they will be sorted at array start

  • leave the filesystem set to auto

  • start the array to import the pool

Yes that is how you re-import a zfs pool

  • Author

Could you please tell me how I should format this drive now so that it can be used as a boot drive for the Unraid OS?

image.png

  • Community Expert

You don't need to, run the wizard; select that device for the boot pool and it will take care of that

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