ZFS on FreeBSD
List disks
Using geom:
geom disk list
Or, install lsblk as you would on Linux:
sudo pkg install lsblk
lsblk
Create pool
Create a basic mirror pool:
zpool create tank mirror /dev/da0 /dev/da1
Create a striped-mirror pool (similar to raid-10):
zpool create tank mirror /dev/da0 /dev/da1 mirror /dev/da2 /dev/da3
Replace a Failed Disk
Failed disk in array
mirror-2 DEGRADED 0 0 0
da2 ONLINE 0 0 0
6017198632328599818 FAULTED 0 0 0 was /dev/da1
da3 ONLINE 0 0 0
Find the ID of the failed disk
geom disk list | less
Geom name: da0
Providers:
1. Name: da0
Mediasize: 2000398934016 (1.8T)
...
descr: ATA WDC WD2002FFSX-6
lunid: 50014ee2c137727d
ident: WD-WCC6N1VSFLSC
...
Find this disk in the system. Yank it. Replace it.
Repeat this to find the ID of the new disk.
Replace the failed disk:
zpool replace tank 6017198632328599818 /dev/da0
Check the status of the resilver:
zpool status tank
state: DEGRADED
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scan: resilver in progress since Mon Mar 17 19:04:42 2025
283G scanned at 2.86G/s, 184G issued at 1.86G/s, 859G total
0B resilvered, 21.39% done, 00:06:03 to go
NAME STATE READ WRITE CKSUM
tank DEGRADED 0 0 0
...
mirror-2 DEGRADED 0 0 0
da2 ONLINE 0 0 0
replacing-1 DEGRADED 0 0 0
6017198632328599818 FAULTED 0 0 0 was /dev/da1
da0 ONLINE 0 0 0
da3 ONLINE 0 0 0
It will take a minute... Go for a walk.
Create dataset
/tank/backups
zfs create -o compress=lz4 tank/backups
Snapshots
Take a snapshot:
sudo zfs snapshot -r zroot@now
Take a snapshot, with an automatically generated name:
sudo zfs snapshot -r zroot@$(date "+%Y%m%d%H%M.%S")
List available snapshots:
zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT
zroot@2021-06-30 0B - 96K -
Delete a snapshot:
sudo zfs destroy zroot@2021-06-30
Compare a snapshot state:
zfs diff zroot/usr/home@202107011206.09
Password:
M /usr/home/noah/.bash_history
+ /usr/home/noah/Desktop/1.txt
+ /usr/home/noah/Desktop/2.txt
+ /usr/home/noah/Desktop/3.txt
+ /usr/home/noah/Desktop/4.txt
M /usr/home/noah/Desktop
Devices
List pools:
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
zroot 37.5G 3.23G 34.3G - - 1% 8% 1.00x ONLINE -
Check device health:
zpool status
pool: zroot
state: ONLINE
config:
NAME STATE READ WRITE CKSUM
zroot ONLINE 0 0 0
vtbd0p3.eli ONLINE 0 0 0
errors: No known data errors
Scrubs
Perform a disk scrub
sudo zpool scrub zroot
Check scrub status:
zpool status
pool: zroot
state: ONLINE
scan: scrub in progress since Tue Jun 29 22:51:19 2021
2.27G scanned at 232M/s, 260K issued at 26K/s, 3.23G total
0B repaired, 0.01% done, no estimated completion time
config:
NAME STATE READ WRITE CKSUM
zroot ONLINE 0 0 0
vtbd0p3.eli ONLINE 0 0 0
errors: No known data errors
Replication
Send a snapshot on the local system, to another array on the local system
zfs send -R -v zroot@202107011210.16 | zfs recv tank/zroot-backup
Send a differential backup based on yesterday's snapshot:
zfs send -R -v -i zroot@202107011210.16 zroot@202107022003.05 | zfs recv tank/zroot-backup
Automatic snapshot script
#!/bin/sh
NUM_SNAPSHOTS=`zfs list -t snapshot zroot | awk '/@/{print $1}' | wc -l`
echo "[+] ${NUM_SNAPSHOTS} snapshots on volume"
echo "[+] Getting last snapshot on system"
LAST_SNAPSHOT=`zfs list -t snapshot zroot | tail -n1 | awk '{print $1}'`
echo "[+] Taking system snapshot"
zfs snapshot -r zroot@$(date "+%Y%m%d-%H%M")
NEW_SNAPSHOT=`zfs list -t snapshot zroot | tail -n1 | awk '{print $1}'`
echo "[+] Sending incremental backup"
zfs send -R -v -i $LAST_SNAPSHOT $NEW_SNAPSHOT | zfs recv tank/zroot-backup
echo "[+] Deleting oldest snapshot"
OLDEST_SNAPSHOT=`zfs list -t snapshot zroot | awk '/@/{print $1}' | head -n1`
zfs destroy -r -v "${OLDEST_SNAPSHOT}"
echo "[+] Deleted snapshot $OLDEST_SNAPSHOT"