ZFS

• Filesystems
• FreeBSD
• ZFS On Linux
• ZFS Administration - the definitive guide to ZFS on Linux
• FreeBSD Handbook: ZFS
• ZFS on FreeBSD
• ZFS Evil Tuning Guide

Do NOT use fuse with ZFS. If there is the slightest hiccup, the filesystem will crash and you will lose all your data.

Use fdisk to edit the partition, and then set the type to bf or Solaris.

Create a new pool named tank using zpool, for example, using /dev/sdb

zpool create tank /dev/sdb

zpool create tank mirror /dev/sdb /dev/sdc

zfs create tank/dataset

zfs create tank/dataset/child

zfs destroy tank/dataset

Useful for upgrading ZFS, moving things around, etc.

zpool export tank
zpool import tank

• Compression and Deduplication

Disable compression:

zfs set compression=off tank/dataset

• Snapshots and Clones
• Displaying and Accessing ZFS Snapshots

ZFS allows you to create incremental snapshots easily enough, using zfs snapshot.

Once a snapshot is created, ZFS will start using new space after data is modified.

Create a snapshot:

zfs snapshot tank/data@snapshot-name

List snapshots:

zfs list -t snapshot

Destroy an old snapshot:

zfs destroy tank/data@snapshot-name

You can access data directly from old snapshots by browsing the .zfs directory in the zfs tree. The directory is hidden by default, and does not need to be toggled as visible to browse. Simply accessing the directory is sufficient.

ls /tank/data/.zfs/snapshot/snapshot-name/

Note: There may be a simpler way to get this using native ZFS tools. Optionally, the .zfs directory can be toggled as visible so that it will show up using ls:

zfs set snapdir=visible tank/data
ls /tank/data/.zfs/snapshot/snapshot-name/
zfs set snapdir=hidden tank/data

On FreeBSD, once you create a zpool or a dataset, it will automatically mount it. It will also mount it at boot.

Add this line to /etc/rc.conf:

zfs_enable="YES"