ZFS on Linux
------------
-include::attributes.txt[]
+ifdef::wiki[]
+:pve-toplevel:
+endif::wiki[]
ZFS is a combined file system and logical volume manager designed by
Sun Microsystems. Starting with {pve} 3.4, the native Linux
kernel port of the ZFS file system is introduced as optional
-file-system and also as an additional selection for the root
-file-system. There is no need for manually compile ZFS modules - all
+file system and also as an additional selection for the root
+file system. There is no need for manually compile ZFS modules - all
packages are included.
-By using ZFS, its possible to achieve maximal enterprise features with
+By using ZFS, its possible to achieve maximum enterprise features with
low budget hardware, but also high performance systems by leveraging
SSD caching or even SSD only setups. ZFS can replace cost intense
hardware raid cards by moderate CPU and memory load combined with easy
* Protection against data corruption
-* Data compression on file-system level
+* Data compression on file system level
* Snapshots
practice, use as much you can get for your hardware/budget. To prevent
data corruption, we recommend the use of high quality ECC RAM.
-If you use a dedicated cache and/or log disk, you should use a
+If you use a dedicated cache and/or log disk, you should use an
enterprise class SSD (e.g. Intel SSD DC S3700 Series). This can
increase the overall performance significantly.
-IMPORTANT: Do not use ZFS on top of hardware controller which has it's
+IMPORTANT: Do not use ZFS on top of hardware controller which has its
own cache management. ZFS needs to directly communicate with disks. An
HBA adapter is the way to go, or something like LSI controller flashed
in ``IT'' mode.
also with `virtio` SCSI controller type).
-Installation as root file system
+Installation as Root File System
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When you install using the {pve} installer, you can choose ZFS for the
the boot loader on all disk required for booting. So you can boot
even if some disks fail.
-NOTE: It is not possible to use ZFS as root partition with UEFI
+NOTE: It is not possible to use ZFS as root file system with UEFI
boot.
# man zfs
-----
-.Create a new ZPool
+.Create a new zpool
To create a new pool, at least one disk is needed. The `ashift` should
have the same sector-size (2 power of `ashift`) or larger as the
zpool create -f -o ashift=12 <pool> <device>
-To activate the compression
+To activate compression
zfs set compression=lz4 <pool>
zpool create -f -o ashift=12 <pool> raidz2 <device1> <device2> <device3> <device4>
-.Create a new pool with Cache (L2ARC)
+.Create a new pool with cache (L2ARC)
It is possible to use a dedicated cache drive partition to increase
the performance (use SSD).
zpool create -f -o ashift=12 <pool> <device> cache <cache_device>
-.Create a new pool with Log (ZIL)
+.Create a new pool with log (ZIL)
It is possible to use a dedicated cache drive partition to increase
the performance(SSD).
zpool create -f -o ashift=12 <pool> <device> log <log_device>
-.Add Cache and Log to an existing pool
+.Add cache and log to an existing pool
If you have an pool without cache and log. First partition the SSD in
2 partition with `parted` or `gdisk`
-IMPORTANT: Always use GPT partition tables (gdisk or parted).
+IMPORTANT: Always use GPT partition tables.
The maximum size of a log device should be about half the size of
physical memory, so this is usually quite small. The rest of the SSD
-can be used to the cache.
+can be used as cache.
zpool add -f <pool> log <device-part1> cache <device-part2>
-.Changing a failed Device
+.Changing a failed device
zpool replace -f <pool> <old device> <new-device>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ZFS comes with an event daemon, which monitors events generated by the
-ZFS kernel module. The daemon can also send E-Mails on ZFS event like
-pool errors.
+ZFS kernel module. The daemon can also send emails on ZFS events like
+pool errors. Newer ZFS packages ships the daemon in a separate package,
+and you can install it using `apt-get`:
+
+----
+# apt-get install zfs-zed
+----
To activate the daemon it is necessary to edit `/etc/zfs/zed.d/zed.rc` with your
favourite editor, and uncomment the `ZED_EMAIL_ADDR` setting:
+--------
ZED_EMAIL_ADDR="root"
+--------
Please note {pve} forwards mails to `root` to the email address
configured for the root user.
other settings are optional.
-Limit ZFS memory usage
+Limit ZFS Memory Usage
~~~~~~~~~~~~~~~~~~~~~~
-It is good to use maximal 50 percent (which is the default) of the
+It is good to use at most 50 percent (which is the default) of the
system memory for ZFS ARC to prevent performance shortage of the
host. Use your preferred editor to change the configuration in
`/etc/modprobe.d/zfs.conf` and insert:
- options zfs zfs_arc_max=8589934592
+--------
+options zfs zfs_arc_max=8589934592
+--------
This example setting limits the usage to 8GB.
[IMPORTANT]
====
-If your root fs is ZFS you must update your initramfs every
-time this value changes.
+If your root file system is ZFS you must update your initramfs every
+time this value changes:
update-initramfs -u
====
To make the swappiness persistent, open `/etc/sysctl.conf` with
an editor of your choice and add the following line:
- vm.swappiness = 10
+--------
+vm.swappiness = 10
+--------
.Linux kernel `swappiness` parameter values
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