How do I add a second mirrored cache drive, ideally as ZFS, with current XFS cache drive

[wayner]

My system right now has an NVME drive used as a single cache 500GB drive that is formatted as XFS.  When I switched from 6.11.5 to 6.12.4 I had BTRFS corruption problems so I reformatted as XFS.  To protect my cache I want to add a second cache drive that would be mirrored.  I added a second 500GB NVME drive to the system but right now it is not yet formatted and shows up in unRAID under Disk Devices.

 

My understanding is that the disk has to be formatted as BTRFS or ZFS to be able to mirror the drive, at least as a cache drive.  Is that correct?  If so then I want to use ZFS due to my prior issues with BTRFS.  I am pretty sure that ZFS can be used in this way but the unRAID docs don't appear to be updated to reflect this.

 

If so then what is the best way to move to a dual cache config?  Can I format my new NVME drive as a ZFS, stop the docker service and VM service and manually copy all of the files from the existing cache drive to this unassigned ZFS drive,  and then make this the cache drive?  And then once I am sure that this is working then reformat the old cache drive to ZFS, increase the number of cache slots to two, and add this to the second slot cache drive?  Would that be the easiest way?  This way I only have to copy the files on the cache data once.

 

Or is it better to just stop docker+VM, copy everything from the cache drive to the pools using mover and then create my two new cache drives formatted as ZFS and use mover to move everything back?

[JorgeB]

11 hours ago, wayner said:

Is that correct?

Yes.

 

11 hours ago, wayner said:

Can I format my new NVME drive as a ZFS, stop the docker service and VM service and manually copy all of the files from the existing cache drive to this unassigned ZFS drive,  and then make this the cache drive?  And then once I am sure that this is working then reformat the old cache drive to ZFS, increase the number of cache slots to two, and add this to the second slot cache drive?  Would that be the easiest way?  This way I only have to copy the files on the cache data once.

That works, don't forget to update the paths for the Docker and VM services after copying them to the new pool.

[wayner]

What do you mean by update paths?  Would I have to use a new pool name for the new cache disk, like NewCache, and make the new NVME disk part of this pool?  And then add the old cache disk to this pool and delete the old pool?  Is that what you mean?

 

And would I then have to update the path for every docker, or just the Docker Config for the server?

[JorgeB]

If docker image and/or libvirt.img and the vdisks are for example using /mnt/user/share or /mnt/old_pool_name/share change them to /mnt/new_pool_name/share

[wayner]

Thanks