8 ZFS is a combined file system and logical volume manager designed by
9 Sun Microsystems. Starting with {pve} 3.4, the native Linux
10 kernel port of the ZFS file system is introduced as optional
11 file system and also as an additional selection for the root
12 file system. There is no need for manually compile ZFS modules - all
13 packages are included.
15 By using ZFS, its possible to achieve maximum enterprise features with
16 low budget hardware, but also high performance systems by leveraging
17 SSD caching or even SSD only setups. ZFS can replace cost intense
18 hardware raid cards by moderate CPU and memory load combined with easy
21 .General ZFS advantages
23 * Easy configuration and management with {pve} GUI and CLI.
27 * Protection against data corruption
29 * Data compression on file system level
35 * Various raid levels: RAID0, RAID1, RAID10, RAIDZ-1, RAIDZ-2 and RAIDZ-3
37 * Can use SSD for cache
41 * Continuous integrity checking
43 * Designed for high storage capacities
45 * Protection against data corruption
47 * Asynchronous replication over network
59 ZFS depends heavily on memory, so you need at least 8GB to start. In
60 practice, use as much you can get for your hardware/budget. To prevent
61 data corruption, we recommend the use of high quality ECC RAM.
63 If you use a dedicated cache and/or log disk, you should use an
64 enterprise class SSD (e.g. Intel SSD DC S3700 Series). This can
65 increase the overall performance significantly.
67 IMPORTANT: Do not use ZFS on top of hardware controller which has its
68 own cache management. ZFS needs to directly communicate with disks. An
69 HBA adapter is the way to go, or something like LSI controller flashed
72 If you are experimenting with an installation of {pve} inside a VM
73 (Nested Virtualization), don't use `virtio` for disks of that VM,
74 since they are not supported by ZFS. Use IDE or SCSI instead (works
75 also with `virtio` SCSI controller type).
78 Installation as Root File System
79 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
81 When you install using the {pve} installer, you can choose ZFS for the
82 root file system. You need to select the RAID type at installation
86 RAID0:: Also called ``striping''. The capacity of such volume is the sum
87 of the capacities of all disks. But RAID0 does not add any redundancy,
88 so the failure of a single drive makes the volume unusable.
90 RAID1:: Also called ``mirroring''. Data is written identically to all
91 disks. This mode requires at least 2 disks with the same size. The
92 resulting capacity is that of a single disk.
94 RAID10:: A combination of RAID0 and RAID1. Requires at least 4 disks.
96 RAIDZ-1:: A variation on RAID-5, single parity. Requires at least 3 disks.
98 RAIDZ-2:: A variation on RAID-5, double parity. Requires at least 4 disks.
100 RAIDZ-3:: A variation on RAID-5, triple parity. Requires at least 5 disks.
102 The installer automatically partitions the disks, creates a ZFS pool
103 called `rpool`, and installs the root file system on the ZFS subvolume
106 Another subvolume called `rpool/data` is created to store VM
107 images. In order to use that with the {pve} tools, the installer
108 creates the following configuration entry in `/etc/pve/storage.cfg`:
114 content images,rootdir
117 After installation, you can view your ZFS pool status using the
127 NAME STATE READ WRITE CKSUM
129 mirror-0 ONLINE 0 0 0
132 mirror-1 ONLINE 0 0 0
136 errors: No known data errors
139 The `zfs` command is used configure and manage your ZFS file
140 systems. The following command lists all file systems after
145 NAME USED AVAIL REFER MOUNTPOINT
146 rpool 4.94G 7.68T 96K /rpool
147 rpool/ROOT 702M 7.68T 96K /rpool/ROOT
148 rpool/ROOT/pve-1 702M 7.68T 702M /
149 rpool/data 96K 7.68T 96K /rpool/data
150 rpool/swap 4.25G 7.69T 64K -
157 Depending on whether the system is booted in EFI or legacy BIOS mode the
158 {pve} installer sets up either `grub` or `systemd-boot` as main bootloader.
159 See the chapter on xref:sysboot[{pve} host bootladers] for details.
165 This section gives you some usage examples for common tasks. ZFS
166 itself is really powerful and provides many options. The main commands
167 to manage ZFS are `zfs` and `zpool`. Both commands come with great
168 manual pages, which can be read with:
177 To create a new pool, at least one disk is needed. The `ashift` should
178 have the same sector-size (2 power of `ashift`) or larger as the
181 zpool create -f -o ashift=12 <pool> <device>
183 To activate compression
185 zfs set compression=lz4 <pool>
187 .Create a new pool with RAID-0
191 zpool create -f -o ashift=12 <pool> <device1> <device2>
193 .Create a new pool with RAID-1
197 zpool create -f -o ashift=12 <pool> mirror <device1> <device2>
199 .Create a new pool with RAID-10
203 zpool create -f -o ashift=12 <pool> mirror <device1> <device2> mirror <device3> <device4>
205 .Create a new pool with RAIDZ-1
209 zpool create -f -o ashift=12 <pool> raidz1 <device1> <device2> <device3>
211 .Create a new pool with RAIDZ-2
215 zpool create -f -o ashift=12 <pool> raidz2 <device1> <device2> <device3> <device4>
217 .Create a new pool with cache (L2ARC)
219 It is possible to use a dedicated cache drive partition to increase
220 the performance (use SSD).
222 As `<device>` it is possible to use more devices, like it's shown in
223 "Create a new pool with RAID*".
225 zpool create -f -o ashift=12 <pool> <device> cache <cache_device>
227 .Create a new pool with log (ZIL)
229 It is possible to use a dedicated cache drive partition to increase
230 the performance(SSD).
232 As `<device>` it is possible to use more devices, like it's shown in
233 "Create a new pool with RAID*".
235 zpool create -f -o ashift=12 <pool> <device> log <log_device>
237 .Add cache and log to an existing pool
239 If you have a pool without cache and log. First partition the SSD in
240 2 partition with `parted` or `gdisk`
242 IMPORTANT: Always use GPT partition tables.
244 The maximum size of a log device should be about half the size of
245 physical memory, so this is usually quite small. The rest of the SSD
246 can be used as cache.
248 zpool add -f <pool> log <device-part1> cache <device-part2>
250 .Changing a failed device
252 zpool replace -f <pool> <old device> <new device>
254 .Changing a failed bootable device when using systemd-boot
256 sgdisk <healthy bootable device> -R <new device>
257 sgdisk -G <new device>
258 zpool replace -f <pool> <old zfs partition> <new zfs partition>
259 pve-efiboot-tool format <new disk's ESP>
260 pve-efiboot-tool init <new disk's ESP>
262 NOTE: `ESP` stands for EFI System Partition, which is setup as partition #2 on
263 bootable disks setup by the {pve} installer since version 5.4. For details, see
264 xref:sysboot_systemd_boot_setup[Setting up a new partition for use as synced ESP].
267 Activate E-Mail Notification
268 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
270 ZFS comes with an event daemon, which monitors events generated by the
271 ZFS kernel module. The daemon can also send emails on ZFS events like
272 pool errors. Newer ZFS packages ship the daemon in a separate package,
273 and you can install it using `apt-get`:
276 # apt-get install zfs-zed
279 To activate the daemon it is necessary to edit `/etc/zfs/zed.d/zed.rc` with your
280 favourite editor, and uncomment the `ZED_EMAIL_ADDR` setting:
283 ZED_EMAIL_ADDR="root"
286 Please note {pve} forwards mails to `root` to the email address
287 configured for the root user.
289 IMPORTANT: The only setting that is required is `ZED_EMAIL_ADDR`. All
290 other settings are optional.
293 Limit ZFS Memory Usage
294 ~~~~~~~~~~~~~~~~~~~~~~
296 It is good to use at most 50 percent (which is the default) of the
297 system memory for ZFS ARC to prevent performance shortage of the
298 host. Use your preferred editor to change the configuration in
299 `/etc/modprobe.d/zfs.conf` and insert:
302 options zfs zfs_arc_max=8589934592
305 This example setting limits the usage to 8GB.
309 If your root file system is ZFS you must update your initramfs every
310 time this value changes:
320 Swap-space created on a zvol may generate some troubles, like blocking the
321 server or generating a high IO load, often seen when starting a Backup
322 to an external Storage.
324 We strongly recommend to use enough memory, so that you normally do not
325 run into low memory situations. Should you need or want to add swap, it is
326 preferred to create a partition on a physical disk and use it as swapdevice.
327 You can leave some space free for this purpose in the advanced options of the
328 installer. Additionally, you can lower the
329 ``swappiness'' value. A good value for servers is 10:
331 sysctl -w vm.swappiness=10
333 To make the swappiness persistent, open `/etc/sysctl.conf` with
334 an editor of your choice and add the following line:
340 .Linux kernel `swappiness` parameter values
341 [width="100%",cols="<m,2d",options="header"]
342 |===========================================================
344 | vm.swappiness = 0 | The kernel will swap only to avoid
345 an 'out of memory' condition
346 | vm.swappiness = 1 | Minimum amount of swapping without
347 disabling it entirely.
348 | vm.swappiness = 10 | This value is sometimes recommended to
349 improve performance when sufficient memory exists in a system.
350 | vm.swappiness = 60 | The default value.
351 | vm.swappiness = 100 | The kernel will swap aggressively.
352 |===========================================================
355 Encrypted ZFS Datasets
356 ~~~~~~~~~~~~~~~~~~~~~~
358 ZFS on Linux version 0.8.0 introduced support for native encryption of
359 datasets. After an upgrade from previous ZFS on Linux versions, the encryption
360 feature can be enabled per pool:
363 # zpool get feature@encryption tank
364 NAME PROPERTY VALUE SOURCE
365 tank feature@encryption disabled local
367 # zpool set feature@encryption=enabled
369 # zpool get feature@encryption tank
370 NAME PROPERTY VALUE SOURCE
371 tank feature@encryption enabled local
374 WARNING: There is currently no support for booting from pools with encrypted
375 datasets using Grub, and only limited support for automatically unlocking
376 encrypted datasets on boot. Older versions of ZFS without encryption support
377 will not be able to decrypt stored data.
379 NOTE: It is recommended to either unlock storage datasets manually after
380 booting, or to write a custom unit to pass the key material needed for
381 unlocking on boot to `zfs load-key`.
383 WARNING: Establish and test a backup procedure before enabling encryption of
384 production data. If the associated key material/passphrase/keyfile has been
385 lost, accessing the encrypted data is no longer possible.
387 Encryption needs to be setup when creating datasets/zvols, and is inherited by
388 default to child datasets. For example, to create an encrypted dataset
389 `tank/encrypted_data` and configure it as storage in {pve}, run the following
393 # zfs create -o encryption=on -o keyformat=passphrase tank/encrypted_data
397 # pvesm add zfspool encrypted_zfs -pool tank/encrypted_data
400 All guest volumes/disks create on this storage will be encrypted with the
401 shared key material of the parent dataset.
403 To actually use the storage, the associated key material needs to be loaded
407 # zfs load-key tank/encrypted_data
408 Enter passphrase for 'tank/encrypted_data':
411 It is also possible to use a (random) keyfile instead of prompting for a
412 passphrase by setting the `keylocation` and `keyformat` properties, either at
413 creation time or with `zfs change-key` on existing datasets:
416 # dd if=/dev/urandom of=/path/to/keyfile bs=32 count=1
418 # zfs change-key -o keyformat=raw -o keylocation=file:///path/to/keyfile tank/encrypted_data
421 WARNING: When using a keyfile, special care needs to be taken to secure the
422 keyfile against unauthorized access or accidental loss. Without the keyfile, it
423 is not possible to access the plaintext data!
425 A guest volume created underneath an encrypted dataset will have its
426 `encryptionroot` property set accordingly. The key material only needs to be
427 loaded once per encryptionroot to be available to all encrypted datasets
430 See the `encryptionroot`, `encryption`, `keylocation`, `keyformat` and
431 `keystatus` properties, the `zfs load-key`, `zfs unload-key` and `zfs
432 change-key` commands and the `Encryption` section from `man zfs` for more
433 details and advanced usage.