7 ZFS is a combined file system and logical volume manager designed by
8 Sun Microsystems. Starting with {pve} 3.4, the native Linux
9 kernel port of the ZFS file system is introduced as optional
10 file system and also as an additional selection for the root
11 file system. There is no need for manually compile ZFS modules - all
12 packages are included.
14 By using ZFS, its possible to achieve maximum enterprise features with
15 low budget hardware, but also high performance systems by leveraging
16 SSD caching or even SSD only setups. ZFS can replace cost intense
17 hardware raid cards by moderate CPU and memory load combined with easy
20 .General ZFS advantages
22 * Easy configuration and management with {pve} GUI and CLI.
26 * Protection against data corruption
28 * Data compression on file system level
34 * Various raid levels: RAID0, RAID1, RAID10, RAIDZ-1, RAIDZ-2 and RAIDZ-3
36 * Can use SSD for cache
40 * Continuous integrity checking
42 * Designed for high storage capacities
44 * Protection against data corruption
46 * Asynchronous replication over network
58 ZFS depends heavily on memory, so you need at least 8GB to start. In
59 practice, use as much you can get for your hardware/budget. To prevent
60 data corruption, we recommend the use of high quality ECC RAM.
62 If you use a dedicated cache and/or log disk, you should use an
63 enterprise class SSD (e.g. Intel SSD DC S3700 Series). This can
64 increase the overall performance significantly.
66 IMPORTANT: Do not use ZFS on top of hardware controller which has its
67 own cache management. ZFS needs to directly communicate with disks. An
68 HBA adapter is the way to go, or something like LSI controller flashed
71 If you are experimenting with an installation of {pve} inside a VM
72 (Nested Virtualization), don't use `virtio` for disks of that VM,
73 since they are not supported by ZFS. Use IDE or SCSI instead (works
74 also with `virtio` SCSI controller type).
77 Installation as Root File System
78 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
80 When you install using the {pve} installer, you can choose ZFS for the
81 root file system. You need to select the RAID type at installation
85 RAID0:: Also called ``striping''. The capacity of such volume is the sum
86 of the capacities of all disks. But RAID0 does not add any redundancy,
87 so the failure of a single drive makes the volume unusable.
89 RAID1:: Also called ``mirroring''. Data is written identically to all
90 disks. This mode requires at least 2 disks with the same size. The
91 resulting capacity is that of a single disk.
93 RAID10:: A combination of RAID0 and RAID1. Requires at least 4 disks.
95 RAIDZ-1:: A variation on RAID-5, single parity. Requires at least 3 disks.
97 RAIDZ-2:: A variation on RAID-5, double parity. Requires at least 4 disks.
99 RAIDZ-3:: A variation on RAID-5, triple parity. Requires at least 5 disks.
101 The installer automatically partitions the disks, creates a ZFS pool
102 called `rpool`, and installs the root file system on the ZFS subvolume
105 Another subvolume called `rpool/data` is created to store VM
106 images. In order to use that with the {pve} tools, the installer
107 creates the following configuration entry in `/etc/pve/storage.cfg`:
113 content images,rootdir
116 After installation, you can view your ZFS pool status using the
126 NAME STATE READ WRITE CKSUM
128 mirror-0 ONLINE 0 0 0
131 mirror-1 ONLINE 0 0 0
135 errors: No known data errors
138 The `zfs` command is used configure and manage your ZFS file
139 systems. The following command lists all file systems after
144 NAME USED AVAIL REFER MOUNTPOINT
145 rpool 4.94G 7.68T 96K /rpool
146 rpool/ROOT 702M 7.68T 96K /rpool/ROOT
147 rpool/ROOT/pve-1 702M 7.68T 702M /
148 rpool/data 96K 7.68T 96K /rpool/data
149 rpool/swap 4.25G 7.69T 64K -
156 The default ZFS disk partitioning scheme does not use the first 2048
157 sectors. This gives enough room to install a GRUB boot partition. The
158 {pve} installer automatically allocates that space, and installs the
159 GRUB boot loader there. If you use a redundant RAID setup, it installs
160 the boot loader on all disk required for booting. So you can boot
161 even if some disks fail.
163 NOTE: It is not possible to use ZFS as root file system with UEFI
170 This section gives you some usage examples for common tasks. ZFS
171 itself is really powerful and provides many options. The main commands
172 to manage ZFS are `zfs` and `zpool`. Both commands come with great
173 manual pages, which can be read with:
182 To create a new pool, at least one disk is needed. The `ashift` should
183 have the same sector-size (2 power of `ashift`) or larger as the
186 zpool create -f -o ashift=12 <pool> <device>
188 To activate compression
190 zfs set compression=lz4 <pool>
192 .Create a new pool with RAID-0
196 zpool create -f -o ashift=12 <pool> <device1> <device2>
198 .Create a new pool with RAID-1
202 zpool create -f -o ashift=12 <pool> mirror <device1> <device2>
204 .Create a new pool with RAID-10
208 zpool create -f -o ashift=12 <pool> mirror <device1> <device2> mirror <device3> <device4>
210 .Create a new pool with RAIDZ-1
214 zpool create -f -o ashift=12 <pool> raidz1 <device1> <device2> <device3>
216 .Create a new pool with RAIDZ-2
220 zpool create -f -o ashift=12 <pool> raidz2 <device1> <device2> <device3> <device4>
222 .Create a new pool with cache (L2ARC)
224 It is possible to use a dedicated cache drive partition to increase
225 the performance (use SSD).
227 As `<device>` it is possible to use more devices, like it's shown in
228 "Create a new pool with RAID*".
230 zpool create -f -o ashift=12 <pool> <device> cache <cache_device>
232 .Create a new pool with log (ZIL)
234 It is possible to use a dedicated cache drive partition to increase
235 the performance(SSD).
237 As `<device>` it is possible to use more devices, like it's shown in
238 "Create a new pool with RAID*".
240 zpool create -f -o ashift=12 <pool> <device> log <log_device>
242 .Add cache and log to an existing pool
244 If you have an pool without cache and log. First partition the SSD in
245 2 partition with `parted` or `gdisk`
247 IMPORTANT: Always use GPT partition tables.
249 The maximum size of a log device should be about half the size of
250 physical memory, so this is usually quite small. The rest of the SSD
251 can be used as cache.
253 zpool add -f <pool> log <device-part1> cache <device-part2>
255 .Changing a failed device
257 zpool replace -f <pool> <old device> <new-device>
260 Activate E-Mail Notification
261 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
263 ZFS comes with an event daemon, which monitors events generated by the
264 ZFS kernel module. The daemon can also send emails on ZFS events like
265 pool errors. Newer ZFS packages ships the daemon in a sparate package,
266 and you can install it using `apt-get`:
269 # apt-get install zfs-zed
272 To activate the daemon it is necessary to edit `/etc/zfs/zed.d/zed.rc` with your
273 favourite editor, and uncomment the `ZED_EMAIL_ADDR` setting:
276 ZED_EMAIL_ADDR="root"
279 Please note {pve} forwards mails to `root` to the email address
280 configured for the root user.
282 IMPORTANT: The only setting that is required is `ZED_EMAIL_ADDR`. All
283 other settings are optional.
286 Limit ZFS Memory Usage
287 ~~~~~~~~~~~~~~~~~~~~~~
289 It is good to use at most 50 percent (which is the default) of the
290 system memory for ZFS ARC to prevent performance shortage of the
291 host. Use your preferred editor to change the configuration in
292 `/etc/modprobe.d/zfs.conf` and insert:
295 options zfs zfs_arc_max=8589934592
298 This example setting limits the usage to 8GB.
302 If your root file system is ZFS you must update your initramfs every
303 time this value changes:
311 SWAP on ZFS on Linux may generate some troubles, like blocking the
312 server or generating a high IO load, often seen when starting a Backup
313 to an external Storage.
315 We strongly recommend to use enough memory, so that you normally do not
316 run into low memory situations. Additionally, you can lower the
317 ``swappiness'' value. A good value for servers is 10:
319 sysctl -w vm.swappiness=10
321 To make the swappiness persistent, open `/etc/sysctl.conf` with
322 an editor of your choice and add the following line:
328 .Linux kernel `swappiness` parameter values
329 [width="100%",cols="<m,2d",options="header"]
330 |===========================================================
332 | vm.swappiness = 0 | The kernel will swap only to avoid
333 an 'out of memory' condition
334 | vm.swappiness = 1 | Minimum amount of swapping without
335 disabling it entirely.
336 | vm.swappiness = 10 | This value is sometimes recommended to
337 improve performance when sufficient memory exists in a system.
338 | vm.swappiness = 60 | The default value.
339 | vm.swappiness = 100 | The kernel will swap aggressively.
340 |===========================================================