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ZFS commands

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date: 2021-06-27 12:21:41

categories: linux

firstPublishDate: 2021-06-27 12:21:41

The commands on this page are my notes reading

FreeBSD handbook ZFS chapter

,

OpenZFS - Root on ZFS

and

ZFS Debian wiki

.

Read my other post for reasons to use ZFS

ZFS in Debian Bullseye

and

Setting up root on ZFS

for installing Debian 11 (bullseye) with ZFS.

Concepts

• zpool manages pools
• zfs manages datasets

pool - vdevs - disks
  `- datasets

Usage

• fstab is not used.

Options:

man zfs
man zpool

• create a pool

zpool create poolName /dev/da0

• create a mirror pool

zpool create poolName mirror /dev/ada1 /dev/ada2

• create raidz pool

zpool create poolName raidz /dev/da0 /dev/da1 /dev/da2

• create a dataset

zfs create poolName/datasetName
zfs set compression=lz4 snapdir=visible poolName/datasetName
zfs set copies=2 compression=lz4 snapdir=visible poolName/datasetName

• create a child dataset and all parent datasets

zfs create -p poolName/dataset1/dataset2/childName

• mount/unmount dataset

zfs mount poolName/datasetName
zfs unmount poolName/datasetName

• set mount point in tree

(all files have to be closed)

zfs mountpoint=/path poolName/datasetName

• delete dataset

zfs destroy poolName/datasetName
delete snapshot
zfs destroy poolName/datasetName@snapshotName

• delete pool

zpool destory poolName

• create a dataset snapshot

zfs snapshot poolName/datasetName@snapshotName

The snapshots are available in `dataset mount point`/.zfs/snapshot/

• create a recursive pool snapshot

zfs snapshot -r poolName@snapshotName

• rollback to a snapshot

zfs rollback poolName/datasetName@snapshotName

• check health

zpool status poolName
# show error details (file paths, errors in snapshots,...):
zpool status poolName -v
zpool status -x
all pools are healthy

• when a disk is dead in a raidz pool

zpool offline storage da1
zpool replace storage da1
zpool status storage

• data verification

zpool scrub poolName

• adding and removing devices

zpool attach >> adds disks to a vdev
zpool add    >> adds vdevs to a pool

• replace a functionning device

zpool replace poolName /dev/ada1p3 /dev/ada2p3

• history

zpool history
zpool history poolName

show more info, like snapshot events:

zpool history -i

long history:

zpool history -l

• performance monitoring

zpool iostat
zpool iostat -v

• list datasets

zfs list

• list snapshots

zfs list -t snapshot

• list all

zfs list -t all

• list a dataset and snapshots for this dataset

zfs list -rt all poolName/datasetName

• list snapshots for a dataset

zfs list -rt snapshot poolName/datasetName

• get compression ratio for a dataset

zfs get used,compressratio,compression,logicalused poolName/datasetName

• get all options for a dataset

zfs get all poolName/datasetName

• rename dataset

zfs rename poolName/datasetName poolName/newDatasetName

• rename snapshot

zfs rename poolName/datasetName@snapshotName newSnapshotName

• diff snapshot

diff snapshot to current

zfs diff poolName/datasetName@snapshotName

diff 2 snapshots

zfs diff poolName/datasetName@snapshotName poolName/datasetName@snapshotName2

• set visible snapshot directory

get state:

zfs get snapdir poolName/datasetName
zfs set snapdir=visible poolName/datasetName

• clone snapshot to dataset

zfs clone poolName/datasetName@snapshotName poolName/newDatasetName

show original snapshot name:

zfs get origin poolName/newDatasetName

remove link with snapshot

zfs promote poolName/newDatasetName

• send dataset with ssh

Setup:
+ host:
zfs allow -u user send,snapshot zroot
+ remote:
sysctl vfs.usermount=1
echo vfs.usermount=1 >> /etc/sysctl.conf
zfs create zroot/backup
zfs allow -u user create,mount,receive zroot/backup
# or zfs allow -u receiver compression,mountpoint,mount,create,receive rxpool
chown user /zroot/backup
zfs create zroot/backup/compressed
zfs set compression=lz4 snapdir=visible zroot/backup/compressed

+ command:
zfs send -vp zroot/compressed@e | ssh user@172.16.43.235 zfs recv -Fdv zroot/backup
-v verbose
-p send dataset properties

receive:
-F Force a rollback of the file system to the most recent snapshot
-d Use the full sent snapshot path without the pool name to determine the name of the new snapshot
-v verbose

• send incremental backups

zfs send -vi zroot/compressed@oldSnapshot zroot/compressed@newSnapshot | ssh user@172.16.43.235 zfs recv -dvu zroot/backup
# zfs recv -Fdv also works

- send with ssh example
zfs snapshot zroot/compressed@initial
+ remote:
+ zfs create zroot/tank
+ zfs set compression=lz4 snapdir=visible zroot/tank
+ zfs allow -u user compression,mountpoint,mount,create,receive zroot/tank
+ chown user /zroot/tank
zfs send -v zroot/compressed@initial | ssh user@172.16.43.235 zfs recv -Fd zroot/tank
zfs snapshot zroot/compressed@evening
zfs send -vi initial zroot/compressed@evening | ssh user@172.16.43.235 zfs recv -Fd zroot/tank

• create a pool and a dataset in an empty disk partition

zpool create \
    -o cachefile=/etc/zfs/zpool.cache \
    -o ashift=12 \
    -O acltype=posixacl -O snapdir=visible -O compression=lz4 \
    -O dnodesize=auto -O normalization=formD -O relatime=on \
    -O xattr=sa -O mountpoint=/home/data \
    sandisk /dev/disk/by-id/DISK-part1

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