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
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.
+in ``IT'' mode.
If you are experimenting with an installation of {pve} inside a VM
-(Nested Virtualization), don't use 'virtio' for disks of that VM,
+(Nested Virtualization), don't use `virtio` for disks of that VM,
since they are not supported by ZFS. Use IDE or SCSI instead (works
-also with 'virtio' SCSI controller type).
+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
time:
[horizontal]
-RAID0:: Also called 'striping'. The capacity of such volume is the sum
-of the capacity of all disks. But RAID0 does not add any redundancy,
+RAID0:: Also called ``striping''. The capacity of such volume is the sum
+of the capacities of all disks. But RAID0 does not add any redundancy,
so the failure of a single drive makes the volume unusable.
-RAID1:: Also called mirroring. Data is written identically to all
+RAID1:: Also called ``mirroring''. Data is written identically to all
disks. This mode requires at least 2 disks with the same size. The
resulting capacity is that of a single disk.
RAIDZ-3:: A variation on RAID-5, triple parity. Requires at least 5 disks.
The installer automatically partitions the disks, creates a ZFS pool
-called 'rpool', and installs the root file system on the ZFS subvolume
-'rpool/ROOT/pve-1'.
+called `rpool`, and installs the root file system on the ZFS subvolume
+`rpool/ROOT/pve-1`.
-Another subvolume called 'rpool/data' is created to store VM
+Another subvolume called `rpool/data` is created to store VM
images. In order to use that with the {pve} tools, the installer
-creates the following configuration entry in '/etc/pve/storage.cfg':
+creates the following configuration entry in `/etc/pve/storage.cfg`:
----
zfspool: local-zfs
----
After installation, you can view your ZFS pool status using the
-'zpool' command:
+`zpool` command:
----
# zpool status
errors: No known data errors
----
-The 'zfs' command is used configure and manage your ZFS file
+The `zfs` command is used configure and manage your ZFS file
systems. The following command lists all file systems after
installation:
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.
This section gives you some usage examples for common tasks. ZFS
itself is really powerful and provides many options. The main commands
-to manage ZFS are 'zfs' and 'zpool'. Both commands comes with great
-manual pages, worth to read:
+to manage ZFS are `zfs` and `zpool`. Both commands come with great
+manual pages, which can be read with:
----
# man zpool
# 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
+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
underlying disk.
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).
-As '<device>' it is possible to use more devices, like it's shown in
+As `<device>` it is possible to use more devices, like it's shown in
"Create a new pool with RAID*".
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).
-As '<device>' it is possible to use more devices, like it's shown in
+As `<device>` it is possible to use more devices, like it's shown in
"Create a new pool with RAID*".
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
+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
+ZFS kernel module. The daemon can also send emails on ZFS events like
pool errors.
-To activate the daemon it is necessary to edit /etc/zfs/zed.d/zed.rc with your favored editor, and uncomment the 'ZED_EMAIL_ADDR' setting:
+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
+Please note {pve} forwards mails to `root` to the email address
configured for the root user.
-IMPORTANT: the only settings that is required is ZED_EMAIL_ADDR. All
+IMPORTANT: The only setting that is required is `ZED_EMAIL_ADDR`. All
other settings are optional.
-Limit ZFS memory usage
+Limit ZFS Memory Usage
~~~~~~~~~~~~~~~~~~~~~~
-It is good to use max 50 percent 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:
+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
====
We strongly recommend to use enough memory, so that you normally do not
run into low memory situations. Additionally, you can lower the
-'swappiness' value. A good value for servers is 10:
+``swappiness'' value. A good value for servers is 10:
sysctl -w vm.swappiness=10
-To make the swappiness persistence, open '/etc/sysctl.conf' with
+To make the swappiness persistent, open `/etc/sysctl.conf` with
an editor of your choice and add the following line:
vm.swappiness = 10
-.Linux Kernel 'swappiness' parameter values
+.Linux kernel `swappiness` parameter values
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