Time Machine Backups
Time Machine Backups
Here's one approach to using ZFS for your Time Machine Backups.
Because Time Machine doesn't recognize ZFS datasets as a compatible disk for Time Machine backups, as a work around, we create an HFS+ sparsebundle disk image, store it on a ZFS dataset, and set the mounted image as a backup destination (no "TMShowUnsupportedNetworkVolumes" needed).
1. Create, and mount, a sparsebundle from a ZFS dataset (e.g., with makeImage.sh or Disk Utility.app).
2. Set the sparsebundle as the (active) backup destination:
# tmutil setdestination -a /Volumes/[sparse bundle volume name]
While it has been discussed in heated arguments (e.g., https://github.com/openzfsonosx/zfs/issues/66) I still believe there's at least one ZFS feature I'd like to test with Time Machine: compression.
The hypothesis being that an HFS+ sparsebundle stored on a compressed (gzip, lz4), deduped dataset should yield a compression ratio > 1.0 (previously observed 1.4 with compression=on, dedup=off, FreeBSD network Time Machine drives).