Convert raidz1 to mirror

TrueNAS General
1

I want to convert a 4-disk z1 system to mirrored.My data is backed up so I don’t care if this is a destructive process. My current setup had a disk failure and before I started the re-silvering process, I did some research and decided I would be better off with mirroring. I’ve been looking around and there’s quite a lot of info about going the other way ( mirrored to raidZ1 ) but not much of anything about converting to mirrored. Any help would be greatly appreciated

2

Both ways raidz1 to mirror and mirror to raidz1 is a destroy pool, recreate and restore from backup process.

1 Like
3

Depends on how much of that pool is used. If all of the data fits on a single disk, you can do it without copying to an external or remote medium. At the risk of losing everything, of course.

  • offline one disk
  • create new pool from the single disk
  • copy data from old pool to new pool
  • destroy old pool
  • attach one of the now free three disks to the one holding the data creating a mirror
  • create a second mirror vdev in the new pool from the remaining two disks

HTH,
Patrick

4

On this one, You should only choose this method if you can fit all your data onto the single disk pool and keep the pool usage below the 80-90% recommended range. 95% may be okay but you are risking the pool if it becomes too full for ZFS. We have had users lose all the data in a pool and have to create a new one when they stuffed it in the 95-100% range.

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5

Thanks for the replies! I have all of the data backed up so losing it isn’t a problem. Currently the pool is running degraded since I replaced a defective disk. I didn’t re-silver so the new disk is unused. Is there a way to just start from scratch and create 2 mirrored disks? I’m pretty new to Truenas so I’m not that good yet with modifying the system.

6

Yes, you can destroy the current pool and VDEV and start over with creating the mirror vdev pool.

TrueNAS 25.10 has it like this.
You do it from the Storage dashboard. Export/Disconnect button on right. Confirm to destroy data, delete config and confirm Export/Disconnect. After that, all disks should show as available for a new pool / VDEV creation.