have the same sector-size (2 power of `ashift`) or larger as the
underlying disk.
- zpool create -f -o ashift=12 <pool> <device>
+----
+# zpool create -f -o ashift=12 <pool> <device>
+----
-To activate compression
+To activate compression (see section <<zfs_compression,Compression in ZFS>>):
- zfs set compression=lz4 <pool>
+----
+# zfs set compression=lz4 <pool>
+----
.Create a new pool with RAID-0
-Minimum 1 Disk
+Minimum 1 disk
- zpool create -f -o ashift=12 <pool> <device1> <device2>
+----
+# zpool create -f -o ashift=12 <pool> <device1> <device2>
+----
.Create a new pool with RAID-1
-Minimum 2 Disks
+Minimum 2 disks
- zpool create -f -o ashift=12 <pool> mirror <device1> <device2>
+----
+# zpool create -f -o ashift=12 <pool> mirror <device1> <device2>
+----
.Create a new pool with RAID-10
-Minimum 4 Disks
+Minimum 4 disks
- zpool create -f -o ashift=12 <pool> mirror <device1> <device2> mirror <device3> <device4>
+----
+# zpool create -f -o ashift=12 <pool> mirror <device1> <device2> mirror <device3> <device4>
+----
.Create a new pool with RAIDZ-1
-Minimum 3 Disks
+Minimum 3 disks
- zpool create -f -o ashift=12 <pool> raidz1 <device1> <device2> <device3>
+----
+# zpool create -f -o ashift=12 <pool> raidz1 <device1> <device2> <device3>
+----
.Create a new pool with RAIDZ-2
-Minimum 4 Disks
+Minimum 4 disks
- zpool create -f -o ashift=12 <pool> raidz2 <device1> <device2> <device3> <device4>
+----
+# zpool create -f -o ashift=12 <pool> raidz2 <device1> <device2> <device3> <device4>
+----
.Create a new pool with cache (L2ARC)
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>
+----
+# zpool create -f -o ashift=12 <pool> <device> cache <cache_device>
+----
.Create a new pool with log (ZIL)
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>
+----
+# zpool create -f -o ashift=12 <pool> <device> log <log_device>
+----
.Add cache and log to an existing pool
physical memory, so this is usually quite small. The rest of the SSD
can be used as cache.
- zpool add -f <pool> log <device-part1> cache <device-part2>
+----
+# zpool add -f <pool> log <device-part1> cache <device-part2>
+----
.Changing a failed device
- zpool replace -f <pool> <old device> <new device>
+----
+# zpool replace -f <pool> <old device> <new device>
+----
.Changing a failed bootable device when using systemd-boot
- sgdisk <healthy bootable device> -R <new device>
- sgdisk -G <new device>
- zpool replace -f <pool> <old zfs partition> <new zfs partition>
- pve-efiboot-tool format <new disk's ESP>
- pve-efiboot-tool init <new disk's ESP>
+----
+# sgdisk <healthy bootable device> -R <new device>
+# sgdisk -G <new device>
+# zpool replace -f <pool> <old zfs partition> <new zfs partition>
+# pve-efiboot-tool format <new disk's ESP>
+# pve-efiboot-tool init <new disk's ESP>
+----
NOTE: `ESP` stands for EFI System Partition, which is setup as partition #2 on
bootable disks setup by the {pve} installer since version 5.4. For details, see
If your root file system is ZFS you must update your initramfs every
time this value changes:
- update-initramfs -u
+----
+# update-initramfs -u
+----
====
installer. Additionally, you can lower the
``swappiness'' value. A good value for servers is 10:
- sysctl -w vm.swappiness=10
+----
+# sysctl -w vm.swappiness=10
+----
To make the swappiness persistent, open `/etc/sysctl.conf` with
an editor of your choice and add the following line:
details and advanced usage.
+[[zfs_compression]]
+Compression in ZFS
+~~~~~~~~~~~~~~~~~~
+
+When compression is enabled on a dataset, ZFS tries to compress all *new*
+blocks before writing them and decompresses them on reading. Already
+existing data will not be compressed retroactively.
+
+You can enable compression with:
+
+----
+# zfs set compression=<algorithm> <dataset>
+----
+
+We recommend using the `lz4` algorithm, because it adds very little CPU
+overhead. Other algorithms like `lzjb` and `gzip-N`, where `N` is an
+integer from `1` (fastest) to `9` (best compression ratio), are also
+available. Depending on the algorithm and how compressible the data is,
+having compression enabled can even increase I/O performance.
+
+You can disable compression at any time with:
+
+----
+# zfs set compression=off <dataset>
+----
+
+Again, only new blocks will be affected by this change.
+
+
ZFS Special Device
~~~~~~~~~~~~~~~~~~
file blocks.
A `special` device can improve the speed of a pool consisting of slow spinning
-hard disks with a lot of changing metadata. For example workloads that involve
-creating or deleting a large number of files will benefit from the presence of
-a `special` device. ZFS datasets can be configured to store whole small files
-on the `special` device which can further improve the performance. Use SSDs for
-the `special` device.
+hard disks with a lot of metadata changes. For example workloads that involve
+creating, updating or deleting a large number of files will benefit from the
+presence of a `special` device. ZFS datasets can also be configured to store
+whole small files on the `special` device which can further improve the
+performance. Use fast SSDs for the `special` device.
IMPORTANT: The redundancy of the `special` device should match the one of the
pool, since the `special` device is a point of failure for the whole pool.
.Create a pool with `special` device and RAID-1:
- zpool create -f -o ashift=12 <pool> mirror <device1> <device2> special mirror <device3> <device4>
+----
+# zpool create -f -o ashift=12 <pool> mirror <device1> <device2> special mirror <device3> <device4>
+----
.Add a `special` device to an existing pool with RAID-1:
- zpool add <pool> special mirror <device1> <device2>
+----
+# zpool add <pool> special mirror <device1> <device2>
+----
ZFS datasets expose the `special_small_blocks=<size>` property. `size` can be
`0` to disable storing small file blocks on the `special` device or a power of
blocks smaller than `size` will be allocated on the `special` device.
IMPORTANT: If the value for `special_small_blocks` is greater than or equal to
-the `recordsize` of the dataset, *all* data will be written to the `special`
-device, so be careful!
+the `recordsize` (default `128K`) of the dataset, *all* data will be written to
+the `special` device, so be careful!
Setting the `special_small_blocks` property on a pool will change the default
value of that property for all child ZFS datasets (for example all containers
in the pool will opt in for small file blocks).
-.Opt in for small file blocks pool-wide:
+.Opt in for all file smaller than 4K-blocks pool-wide:
- zfs set special_small_blocks=4K <pool>
+----
+# zfs set special_small_blocks=4K <pool>
+----
.Opt in for small file blocks for a single dataset:
- zfs set special_small_blocks=4K <pool>/<filesystem>
+----
+# zfs set special_small_blocks=4K <pool>/<filesystem>
+----
.Opt out from small file blocks for a single dataset:
- zfs set special_small_blocks=0 <pool>/<filesystem>
+----
+# zfs set special_small_blocks=0 <pool>/<filesystem>
+----
projects / pve-docs.git / blobdiff