3 include::attributes.txt[]
5 ZFS is a combined file system and logical volume manager designed by
6 Sun Microsystems. Starting with {pve} 3.4, the native Linux
7 kernel port of the ZFS file system is introduced as optional
8 file-system and also as an additional selection for the root
9 file-system. There is no need for manually compile ZFS modules - all
10 packages are included.
12 By using ZFS, its possible to achieve maximal enterprise features with
13 low budget hardware, but also high performance systems by leveraging
14 SSD caching or even SSD only setups. ZFS can replace cost intense
15 hardware raid cards by moderate CPU and memory load combined with easy
18 .General ZFS advantages
20 * Easy configuration and management with {pve} GUI and CLI.
24 * Protection against data corruption
26 * Data compression on file-system level
32 * Various raid levels: RAID0, RAID1, RAID10, RAIDZ-1, RAIDZ-2 and RAIDZ-3
34 * Can use SSD for cache
38 * Continuous integrity checking
40 * Designed for high storage capacities
42 * Protection against data corruption
44 * Asynchronous replication over network
56 ZFS depends heavily on memory, so you need at least 8GB to start. In
57 practice, use as much you can get for your hardware/budget. To prevent
58 data corruption, we recommend the use of high quality ECC RAM.
60 If you use a dedicated cache and/or log disk, you should use a
61 enterprise class SSD (e.g. Intel SSD DC S3700 Series). This can
62 increase the overall performance significantly.
64 IMPORTANT: Do not use ZFS on top of hardware controller which has it's
65 own cache management. ZFS needs to directly communicate with disks. An
66 HBA adapter is the way to go, or something like LSI controller flashed
69 If you are experimenting with an installation of {pve} inside a VM
70 (Nested Virtualization), don't use 'virtio' for disks of that VM,
71 since they are not supported by ZFS. Use IDE or SCSI instead (works
72 also with 'virtio' SCSI controller type).
75 Installation as root file system
76 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
78 When you install using the {pve} installer, you can choose ZFS for the
79 root file system. You need to select the RAID type at installation
83 RAID0:: Also called 'striping'. The capacity of such volume is the sum
84 of the capacity of all disks. But RAID0 does not add any redundancy,
85 so the failure of a single drive makes the volume unusable.
87 RAID1:: Also called mirroring. Data is written identically to all
88 disks. This mode requires at least 2 disks with the same size. The
89 resulting capacity is that of a single disk.
91 RAID10:: A combination of RAID0 and RAID1. Requires at least 4 disks.
93 RAIDZ-1:: A variation on RAID-5, single parity. Requires at least 3 disks.
95 RAIDZ-2:: A variation on RAID-5, double parity. Requires at least 4 disks.
97 RAIDZ-3:: A variation on RAID-5, triple parity. Requires at least 5 disks.
99 The installer automatically partitions the disks, creates a ZFS pool
100 called 'rpool', and installs the root file system on the ZFS subvolume
103 Another subvolume called 'rpool/data' is created to store VM
104 images. In order to use that with the {pve} tools, the installer
105 creates the following configuration entry in '/etc/pve/storage.cfg':
111 content images,rootdir
114 After installation, you can view your ZFS pool status using the
124 NAME STATE READ WRITE CKSUM
126 mirror-0 ONLINE 0 0 0
129 mirror-1 ONLINE 0 0 0
133 errors: No known data errors
136 The 'zfs' command is used configure and manage your ZFS file
137 systems. The following command lists all file systems after
142 NAME USED AVAIL REFER MOUNTPOINT
143 rpool 4.94G 7.68T 96K /rpool
144 rpool/ROOT 702M 7.68T 96K /rpool/ROOT
145 rpool/ROOT/pve-1 702M 7.68T 702M /
146 rpool/data 96K 7.68T 96K /rpool/data
147 rpool/swap 4.25G 7.69T 64K -
154 The default ZFS disk partitioning scheme does not use the first 2048
155 sectors. This gives enough room to install a GRUB boot partition. The
156 {pve} installer automatically allocates that space, and installs the
157 GRUB boot loader there. If you use a redundant RAID setup, it installs
158 the boot loader on all disk required for booting. So you can boot
159 even if some disks fail.
161 NOTE: It is not possible to use ZFS as root partition with UEFI
168 This section gives you some usage examples for common tasks. ZFS
169 itself is really powerful and provides many options. The main commands
170 to manage ZFS are 'zfs' and 'zpool'. Both commands comes with great
171 manual pages, worth to read:
180 To create a new pool, at least one disk is needed. The 'ashift' should
181 have the same sector-size (2 power of 'ashift') or larger as the
184 zpool create -f -o ashift=12 <pool> <device>
186 To activate the compression
188 zfs set compression=lz4 <pool>
190 .Create a new pool with RAID-0
194 zpool create -f -o ashift=12 <pool> <device1> <device2>
196 .Create a new pool with RAID-1
200 zpool create -f -o ashift=12 <pool> mirror <device1> <device2>
202 .Create a new pool with RAID-10
206 zpool create -f -o ashift=12 <pool> mirror <device1> <device2> mirror <device3> <device4>
208 .Create a new pool with RAIDZ-1
212 zpool create -f -o ashift=12 <pool> raidz1 <device1> <device2> <device3>
214 .Create a new pool with RAIDZ-2
218 zpool create -f -o ashift=12 <pool> raidz2 <device1> <device2> <device3> <device4>
220 .Create a new pool with Cache (L2ARC)
222 It is possible to use a dedicated cache drive partition to increase
223 the performance (use SSD).
225 As '<device>' it is possible to use more devices, like it's shown in
226 "Create a new pool with RAID*".
228 zpool create -f -o ashift=12 <pool> <device> cache <cache_device>
230 .Create a new pool with Log (ZIL)
232 It is possible to use a dedicated cache drive partition to increase
233 the performance(SSD).
235 As '<device>' it is possible to use more devices, like it's shown in
236 "Create a new pool with RAID*".
238 zpool create -f -o ashift=12 <pool> <device> log <log_device>
240 .Add Cache and Log to an existing pool
242 If you have an pool without cache and log. First partition the SSD in
243 2 partition with parted or gdisk
245 IMPORTANT: Always use GPT partition tables (gdisk or parted).
247 The maximum size of a log device should be about half the size of
248 physical memory, so this is usually quite small. The rest of the SSD
249 can be used to the cache.
251 zpool add -f <pool> log <device-part1> cache <device-part2>
253 .Changing a failed Device
255 zpool replace -f <pool> <old device> <new-device>
258 Activate E-Mail Notification
259 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
261 ZFS comes with an event daemon, which monitors events generated by the
262 ZFS kernel module. The daemon can also send E-Mails on ZFS event like
265 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:
267 ZED_EMAIL_ADDR="root"
269 Please note {pve} forwards mails to 'root' to the email address
270 configured for the root user.
272 IMPORTANT: the only settings that is required is ZED_EMAIL_ADDR. All
273 other settings are optional.
276 Limit ZFS memory usage
277 ~~~~~~~~~~~~~~~~~~~~~~
279 It is good to use maximal 50 percent (which is the default) of the
280 system memory for ZFS ARC to prevent performance shortage of the
281 host. Use your preferred editor to change the configuration in
282 /etc/modprobe.d/zfs.conf and insert:
284 options zfs zfs_arc_max=8589934592
286 This example setting limits the usage to 8GB.
290 If your root fs is ZFS you must update your initramfs every
291 time this value changes.
299 SWAP on ZFS on Linux may generate some troubles, like blocking the
300 server or generating a high IO load, often seen when starting a Backup
301 to an external Storage.
303 We strongly recommend to use enough memory, so that you normally do not
304 run into low memory situations. Additionally, you can lower the
305 'swappiness' value. A good value for servers is 10:
307 sysctl -w vm.swappiness=10
309 To make the swappiness persistence, open '/etc/sysctl.conf' with
310 an editor of your choice and add the following line:
314 .Linux Kernel 'swappiness' parameter values
315 [width="100%",cols="<m,2d",options="header"]
316 |===========================================================
318 | vm.swappiness = 0 | The kernel will swap only to avoid
319 an 'out of memory' condition
320 | vm.swappiness = 1 | Minimum amount of swapping without
321 disabling it entirely.
322 | vm.swappiness = 10 | This value is sometimes recommended to
323 improve performance when sufficient memory exists in a system.
324 | vm.swappiness = 60 | The default value.
325 | vm.swappiness = 100 | The kernel will swap aggressively.
326 |===========================================================