3 include::attributes.txt[]
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 a
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 The default ZFS disk partitioning scheme does not use the first 2048
158 sectors. This gives enough room to install a GRUB boot partition. The
159 {pve} installer automatically allocates that space, and installs the
160 GRUB boot loader there. If you use a redundant RAID setup, it installs
161 the boot loader on all disk required for booting. So you can boot
162 even if some disks fail.
164 NOTE: It is not possible to use ZFS as root file system with UEFI
171 This section gives you some usage examples for common tasks. ZFS
172 itself is really powerful and provides many options. The main commands
173 to manage ZFS are `zfs` and `zpool`. Both commands come with great
174 manual pages, which can be read with:
183 To create a new pool, at least one disk is needed. The `ashift` should
184 have the same sector-size (2 power of `ashift`) or larger as the
187 zpool create -f -o ashift=12 <pool> <device>
189 To activate compression
191 zfs set compression=lz4 <pool>
193 .Create a new pool with RAID-0
197 zpool create -f -o ashift=12 <pool> <device1> <device2>
199 .Create a new pool with RAID-1
203 zpool create -f -o ashift=12 <pool> mirror <device1> <device2>
205 .Create a new pool with RAID-10
209 zpool create -f -o ashift=12 <pool> mirror <device1> <device2> mirror <device3> <device4>
211 .Create a new pool with RAIDZ-1
215 zpool create -f -o ashift=12 <pool> raidz1 <device1> <device2> <device3>
217 .Create a new pool with RAIDZ-2
221 zpool create -f -o ashift=12 <pool> raidz2 <device1> <device2> <device3> <device4>
223 .Create a new pool with cache (L2ARC)
225 It is possible to use a dedicated cache drive partition to increase
226 the performance (use SSD).
228 As `<device>` it is possible to use more devices, like it's shown in
229 "Create a new pool with RAID*".
231 zpool create -f -o ashift=12 <pool> <device> cache <cache_device>
233 .Create a new pool with log (ZIL)
235 It is possible to use a dedicated cache drive partition to increase
236 the performance(SSD).
238 As `<device>` it is possible to use more devices, like it's shown in
239 "Create a new pool with RAID*".
241 zpool create -f -o ashift=12 <pool> <device> log <log_device>
243 .Add cache and log to an existing pool
245 If you have an pool without cache and log. First partition the SSD in
246 2 partition with `parted` or `gdisk`
248 IMPORTANT: Always use GPT partition tables.
250 The maximum size of a log device should be about half the size of
251 physical memory, so this is usually quite small. The rest of the SSD
252 can be used as cache.
254 zpool add -f <pool> log <device-part1> cache <device-part2>
256 .Changing a failed device
258 zpool replace -f <pool> <old device> <new-device>
261 Activate E-Mail Notification
262 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
264 ZFS comes with an event daemon, which monitors events generated by the
265 ZFS kernel module. The daemon can also send emails on ZFS events like
268 To activate the daemon it is necessary to edit `/etc/zfs/zed.d/zed.rc` with your
269 favourite editor, and uncomment the `ZED_EMAIL_ADDR` setting:
272 ZED_EMAIL_ADDR="root"
275 Please note {pve} forwards mails to `root` to the email address
276 configured for the root user.
278 IMPORTANT: The only setting that is required is `ZED_EMAIL_ADDR`. All
279 other settings are optional.
282 Limit ZFS Memory Usage
283 ~~~~~~~~~~~~~~~~~~~~~~
285 It is good to use at most 50 percent (which is the default) of the
286 system memory for ZFS ARC to prevent performance shortage of the
287 host. Use your preferred editor to change the configuration in
288 `/etc/modprobe.d/zfs.conf` and insert:
291 options zfs zfs_arc_max=8589934592
294 This example setting limits the usage to 8GB.
298 If your root file system is ZFS you must update your initramfs every
299 time this value changes:
307 SWAP on ZFS on Linux may generate some troubles, like blocking the
308 server or generating a high IO load, often seen when starting a Backup
309 to an external Storage.
311 We strongly recommend to use enough memory, so that you normally do not
312 run into low memory situations. Additionally, you can lower the
313 ``swappiness'' value. A good value for servers is 10:
315 sysctl -w vm.swappiness=10
317 To make the swappiness persistent, open `/etc/sysctl.conf` with
318 an editor of your choice and add the following line:
324 .Linux kernel `swappiness` parameter values
325 [width="100%",cols="<m,2d",options="header"]
326 |===========================================================
328 | vm.swappiness = 0 | The kernel will swap only to avoid
329 an 'out of memory' condition
330 | vm.swappiness = 1 | Minimum amount of swapping without
331 disabling it entirely.
332 | vm.swappiness = 10 | This value is sometimes recommended to
333 improve performance when sufficient memory exists in a system.
334 | vm.swappiness = 60 | The default value.
335 | vm.swappiness = 100 | The kernel will swap aggressively.
336 |===========================================================