With a setup with two disk is there a way to migrate from software RAID1 to ZFS mirror ?
This kind of procedure would be inspired by the migration that is possible from a disk stored on a single drive to software RAID1 : setup the software RAID in degraded mode with a missing drive, copy the data, add the first drive to the array.
zpool create -f -m /data data mirror /dev/sdb
invalid vdev specification: mirror requires at least 2 devices
Does anyone know a way of doing this ? With a fake device that writes to null ? Can ZFS change a device from "normal" to "mirror" ?
Best Answer
You would create a single disk device, not a mirror. Then attach a second disk to the first disk; ZFS will automatically know it has to create a Mirror VDEV for you.
insert standard warning about only having a single disk with valid data during this process and intentionally stressing the disks by copy massive amounts of data - backup, backup, backups
Side note: never, never, never use the
-f
argument unless some ZFS Demigod Guru instructs you to do so. I guarantee 99% of the time you don't want to force it and the other 1% of the time you'll end up destroying something.