User Savagedlight shows us how to replace a drive on a FreeBSD system using only one drive and ZFS, without disrupting its availability. Check out the video below for the full walk-through.

Recap of the video

  • Prequisite: A standard FreeBSD 12.0 install with root on ZFS, where the root pool is smaller than the amount of system memory. (in my case: 8GB system memory, 4GB root pool)
  • Replace existing drive with a memory-backed block device
  • Physically remove the existing drive
  • Verify the system still works
  • Physically attach new drive to system
  • Replace memory-backed block device with new drive
  • Bonus: Reboot system, verify it boots from new drive.

Blog:

FreeBSD+ZFS Without Drives