```IN FREENAS '''geom disk list'''
### List all pools
```zpool list```
### Clear device errors from a pool and try to rebuild the pool
```zpool clear```
### Create a zpool called 'files' in RAID 0 using /dev/sd[b,c,d]
```zpool create -f files /dev/sdb /dev/sdc /dev/sdd```
*Optional Parameters*
-m mountpoint
Sets the mount point for the root dataset. The default mount point is /pool or altroot/pool if altroot is specified. The mount
point must be an absolute path, legacy, or none. For more information on dataset mount points, see zfs(8).
### Create a zpool called 'files' in RAID 1 (Mirrored) using /dev/sda and /dev/sdb
```zpool create files mirror /dev/sda /dev/sdb```
*used striped instead of mirror for RAID 5*
### Change the base mountpoint of an existing ZFS Pool called $POOL to $NEWPATH
```zfs set mountpoint=$NEWPATH $POOL```
### Kill a pool named $POOL
```zpool destroy $POOL```
## File Systems
ZFS file systems live 'inside' pools. By default they are mounted under the parent pool.
For example:
zfs get mountpoint big NAME PROPERTY VALUE SOURCE big mountpoint /var/lib/snapd/hostfs/big local
zfs create big/docker # docker is a filesystem in the pool named big
zfs get mountpoint big/docker NAME PROPERTY VALUE SOURCE big/docker mountpoint /var/lib/snapd/hostfs/big/docker inherited from big
As you can see, ```big``` is mounted in ```/var/lib/snapd/hostfs/big``` and ```big/docker``` is mounted in ```/var/lib/snapd/hostfs/big/docker``` and it's that inherited from /big.
But what if we want big/docker to be mounted in /var/lib/docker?
zfs set mountpoint=/var/lib/docker big/docker
zfs get mountpoint big/docker NAME PROPERTY VALUE SOURCE big/docker mountpoint /var/lib/docker local
### List file systems
* `zfs list` shows all file systems
* `zfs list -r small` shows all file systems under small
* `zfs list -t snapshot` shows all snapshots
## Snapshots
Snapshots capture a point in time of a file system. Snapshots can't be accessed directly, but you can clone them, back them up, and roll back to them.
### Create a snapshot
To create a filesystem snapshot, we use the `zfs snapshot` command.
We have a filesystem called test, mounted in my home directory.
zfs list -r big/test NAME USED AVAIL REFER MOUNTPOINT big/test 96K 4.36T 96K /home/mrunkel/test
I create a snapshot of the filesystem.
zfs snapshot big/test@demo zfs list -t snapshot NAME USED AVAIL REFER MOUNTPOINT big/test@demo 0B - 96K -
# Rollback a snapshot
Now let's create a file in there.
touch /home/mrunkel/test/afile.txt ls /home/mrunkel/test/ afile.txt
Now let's rollback to the snapshot.
```zfs rollback big/test@demo ls /home/mrunkel/test/
You can make a copy of a snapshot into a new filesystem..
Here we take the snapshot we created above big/test@demo and create a new
zfs filesystem big/demobackup from it.
> zfs clone big/test@demo big/demobackup
Note: Snapshots that are used to create cloned file systems can't be deleted until the file system is deleted.
You can also 'send' your snapshot to another machine..
Here we're sending the big/test@demo snapshot to othermachine into the backup/test filesystem.
zfs send big/test@demo | ssh othermachine zfs recv backup/test
Obviously, the other machine will also need to have ZFS installed