X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=local-zfs.adoc;h=014f5874b015a259b997d9be78898424e3819c77;hb=067d9c3dba03e99d5e1873f13ec7c4786f5151d3;hp=48196781f0d3bf6dc7bbd4460037216514f868d5;hpb=9060abb976b945acd1eab2ba12d3dba2bdb8c42c;p=pve-docs.git diff --git a/local-zfs.adoc b/local-zfs.adoc index 4819678..014f587 100644 --- a/local-zfs.adoc +++ b/local-zfs.adoc @@ -32,7 +32,8 @@ management. * Copy-on-write clone -* Various raid levels: RAID0, RAID1, RAID10, RAIDZ-1, RAIDZ-2 and RAIDZ-3 +* Various raid levels: RAID0, RAID1, RAID10, RAIDZ-1, RAIDZ-2, RAIDZ-3, +dRAID, dRAID2, dRAID3 * Can use SSD for cache @@ -55,22 +56,22 @@ Hardware ~~~~~~~~ ZFS depends heavily on memory, so you need at least 8GB to start. In -practice, use as much you can get for your hardware/budget. To prevent +practice, use as much as you can get for your hardware/budget. To prevent data corruption, we recommend the use of high quality ECC RAM. If you use a dedicated cache and/or log disk, you should use an -enterprise class SSD (e.g. Intel SSD DC S3700 Series). This can +enterprise class SSD. This can increase the overall performance significantly. -IMPORTANT: Do not use ZFS on top of hardware controller which has its -own cache management. ZFS needs to directly communicate with disks. An -HBA adapter is the way to go, or something like LSI controller flashed -in ``IT'' mode. +IMPORTANT: Do not use ZFS on top of a hardware RAID controller which has its +own cache management. ZFS needs to communicate directly with the disks. An +HBA adapter or something like an LSI controller flashed in ``IT'' mode is more +appropriate. If you are experimenting with an installation of {pve} inside a VM (Nested Virtualization), don't use `virtio` for disks of that VM, -since they are not supported by ZFS. Use IDE or SCSI instead (works -also with `virtio` SCSI controller type). +as they are not supported by ZFS. Use IDE or SCSI instead (also works +with the `virtio` SCSI controller type). Installation as Root File System @@ -166,17 +167,17 @@ Each `vdev` type has different performance behaviors. The two parameters of interest are the IOPS (Input/Output Operations per Second) and the bandwidth with which data can be written or read. -A 'mirror' vdev (RAID1) will approximately behave like a single disk in regards -to both parameters when writing data. When reading data if will behave like the -number of disks in the mirror. +A 'mirror' vdev (RAID1) will approximately behave like a single disk in regard +to both parameters when writing data. When reading data the performance will +scale linearly with the number of disks in the mirror. A common situation is to have 4 disks. When setting it up as 2 mirror vdevs (RAID10) the pool will have the write characteristics as two single disks in -regard of IOPS and bandwidth. For read operations it will resemble 4 single +regard to IOPS and bandwidth. For read operations it will resemble 4 single disks. A 'RAIDZ' of any redundancy level will approximately behave like a single disk -in regard of IOPS with a lot of bandwidth. How much bandwidth depends on the +in regard to IOPS with a lot of bandwidth. How much bandwidth depends on the size of the RAIDZ vdev and the redundancy level. For running VMs, IOPS is the more important metric in most situations. @@ -234,7 +235,7 @@ There are a few options to counter the increased use of space: The `volblocksize` property can only be set when creating a ZVOL. The default value can be changed in the storage configuration. When doing this, the guest needs to be tuned accordingly and depending on the use case, the problem of -write amplification if just moved from the ZFS layer up to the guest. +write amplification is just moved from the ZFS layer up to the guest. Using `ashift=9` when creating the pool can lead to bad performance, depending on the disks underneath, and cannot be changed later on. @@ -244,12 +245,53 @@ them, unless your environment has specific needs and characteristics where RAIDZ performance characteristics are acceptable. +ZFS dRAID +~~~~~~~~~ + +In a ZFS dRAID (declustered RAID) the hot spare drive(s) participate in the RAID. +Their spare capacity is reserved and used for rebuilding when one drive fails. +This provides, depending on the configuration, faster rebuilding compared to a +RAIDZ in case of drive failure. More information can be found in the official +OpenZFS documentation. footnote:[OpenZFS dRAID +https://openzfs.github.io/openzfs-docs/Basic%20Concepts/dRAID%20Howto.html] + +NOTE: dRAID is intended for more than 10-15 disks in a dRAID. A RAIDZ +setup should be better for a lower amount of disks in most use cases. + +NOTE: The GUI requires one more disk than the minimum (i.e. dRAID1 needs 3). It +expects that a spare disk is added as well. + + * `dRAID1` or `dRAID`: requires at least 2 disks, one can fail before data is +lost + * `dRAID2`: requires at least 3 disks, two can fail before data is lost + * `dRAID3`: requires at least 4 disks, three can fail before data is lost + + +Additional information can be found on the manual page: + +---- +# man zpoolconcepts +---- + +Spares and Data +^^^^^^^^^^^^^^^ +The number of `spares` tells the system how many disks it should keep ready in +case of a disk failure. The default value is 0 `spares`. Without spares, +rebuilding won't get any speed benefits. + +`data` defines the number of devices in a redundancy group. The default value is +8. Except when `disks - parity - spares` equal something less than 8, the lower +number is used. In general, a smaller number of `data` devices leads to higher +IOPS, better compression ratios and faster resilvering, but defining fewer data +devices reduces the available storage capacity of the pool. + + Bootloader ~~~~~~~~~~ -Depending on whether the system is booted in EFI or legacy BIOS mode the -{pve} installer sets up either `grub` or `systemd-boot` as main bootloader. -See the chapter on xref:sysboot[{pve} host bootladers] for details. +{pve} uses xref:sysboot_proxmox_boot_tool[`proxmox-boot-tool`] to manage the +bootloader configuration. +See the chapter on xref:sysboot[{pve} host bootloaders] for details. ZFS Administration @@ -269,14 +311,23 @@ manual pages, which can be read with: Create a new zpool ^^^^^^^^^^^^^^^^^^ -To create a new pool, at least one disk is needed. The `ashift` should -have the same sector-size (2 power of `ashift`) or larger as the -underlying disk. +To create a new pool, at least one disk is needed. The `ashift` should have the +same sector-size (2 power of `ashift`) or larger as the underlying disk. ---- # zpool create -f -o ashift=12 ---- +[TIP] +==== +Pool names must adhere to the following rules: + +* begin with a letter (a-z or A-Z) +* contain only alphanumeric, `-`, `_`, `.`, `:` or ` ` (space) characters +* must *not begin* with one of `mirror`, `raidz`, `draid` or `spare` +* must not be `log` +==== + To activate compression (see section <>): ---- @@ -364,8 +415,8 @@ As `` it is possible to use more devices, like it's shown in Add cache and log to an existing pool ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -If you have a pool without cache and log. First partition the SSD in -2 partition with `parted` or `gdisk` +If you have a pool without cache and log, first create 2 partitions on the SSD +with `parted` or `gdisk`. IMPORTANT: Always use GPT partition tables. @@ -387,8 +438,15 @@ Changing a failed device .Changing a failed bootable device -Depending on how {pve} was installed it is either using `grub` or `systemd-boot` -as bootloader (see xref:sysboot[Host Bootloader]). +Depending on how {pve} was installed it is either using `systemd-boot` or `grub` +through `proxmox-boot-tool` +footnote:[Systems installed with {pve} 6.4 or later, EFI systems installed with +{pve} 5.4 or later] or plain `grub` as bootloader (see +xref:sysboot[Host Bootloader]). You can check by running: + +---- +# proxmox-boot-tool status +---- The first steps of copying the partition table, reissuing GUIDs and replacing the ZFS partition are the same. To make the system bootable from the new disk, @@ -403,37 +461,37 @@ different steps are needed which depend on the bootloader in use. NOTE: Use the `zpool status -v` command to monitor how far the resilvering process of the new disk has progressed. -.With `systemd-boot`: +.With `proxmox-boot-tool`: ---- -# pve-efiboot-tool format -# pve-efiboot-tool init +# proxmox-boot-tool format +# proxmox-boot-tool init ---- 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 -xref:sysboot_systemd_boot_setup[Setting up a new partition for use as synced ESP]. +xref:sysboot_proxmox_boot_setup[Setting up a new partition for use as synced ESP]. -.With `grub`: +.With plain `grub`: ---- # grub-install ---- +NOTE: plain `grub` is only used on systems installed with {pve} 6.3 or earlier, +which have not been manually migrated to using `proxmox-boot-tool` yet. -Activate E-Mail Notification -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -ZFS comes with an event daemon, which monitors events generated by the -ZFS kernel module. The daemon can also send emails on ZFS events like -pool errors. Newer ZFS packages ship the daemon in a separate package, -and you can install it using `apt-get`: +Configure E-Mail Notification +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ----- -# apt-get install zfs-zed ----- +ZFS comes with an event daemon `ZED`, which monitors events generated by the ZFS +kernel module. The daemon can also send emails on ZFS events like pool errors. +Newer ZFS packages ship the daemon in a separate `zfs-zed` package, which should +already be installed by default in {pve}. -To activate the daemon it is necessary to edit `/etc/zfs/zed.d/zed.rc` with your -favourite editor, and uncomment the `ZED_EMAIL_ADDR` setting: +You can configure the daemon via the file `/etc/zfs/zed.d/zed.rc` with your +favorite editor. The required setting for email notification is +`ZED_EMAIL_ADDR`, which is set to `root` by default. -------- ZED_EMAIL_ADDR="root" @@ -442,9 +500,6 @@ ZED_EMAIL_ADDR="root" Please note {pve} forwards mails to `root` to the email address configured for the root user. -IMPORTANT: The only setting that is required is `ZED_EMAIL_ADDR`. All -other settings are optional. - [[sysadmin_zfs_limit_memory_usage]] Limit ZFS Memory Usage @@ -473,13 +528,26 @@ options zfs zfs_arc_max=8589934592 This example setting limits the usage to 8 GiB ('8 * 2^30^'). +IMPORTANT: In case your desired +zfs_arc_max+ value is lower than or equal to ++zfs_arc_min+ (which defaults to 1/32 of the system memory), +zfs_arc_max+ will +be ignored unless you also set +zfs_arc_min+ to at most +zfs_arc_max - 1+. + +---- +echo "$[8 * 1024*1024*1024 - 1]" >/sys/module/zfs/parameters/zfs_arc_min +echo "$[8 * 1024*1024*1024]" >/sys/module/zfs/parameters/zfs_arc_max +---- + +This example setting (temporarily) limits the usage to 8 GiB ('8 * 2^30^') on +systems with more than 256 GiB of total memory, where simply setting ++zfs_arc_max+ alone would not work. + [IMPORTANT] ==== If your root file system is ZFS, you must update your initramfs every time this value changes: ---- -# update-initramfs -u +# update-initramfs -u -k all ---- You *must reboot* to activate these changes. @@ -496,7 +564,7 @@ to an external Storage. We strongly recommend to use enough memory, so that you normally do not run into low memory situations. Should you need or want to add swap, it is -preferred to create a partition on a physical disk and use it as swapdevice. +preferred to create a partition on a physical disk and use it as a swap device. You can leave some space free for this purpose in the advanced options of the installer. Additionally, you can lower the ``swappiness'' value. A good value for servers is 10: @@ -530,6 +598,12 @@ improve performance when sufficient memory exists in a system. Encrypted ZFS Datasets ~~~~~~~~~~~~~~~~~~~~~~ +WARNING: Native ZFS encryption in {pve} is experimental. Known limitations and +issues include Replication with encrypted datasets +footnote:[https://bugzilla.proxmox.com/show_bug.cgi?id=2350], +as well as checksum errors when using Snapshots or ZVOLs. +footnote:[https://github.com/openzfs/zfs/issues/11688] + ZFS on Linux version 0.8.0 introduced support for native encryption of datasets. After an upgrade from previous ZFS on Linux versions, the encryption feature can be enabled per pool: @@ -671,7 +745,7 @@ WARNING: Adding a `special` device to a pool cannot be undone! ZFS datasets expose the `special_small_blocks=` property. `size` can be `0` to disable storing small file blocks on the `special` device or a power of -two in the range between `512B` to `128K`. After setting the property new file +two in the range between `512B` to `1M`. After setting the property new file 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 @@ -699,3 +773,38 @@ in the pool will opt in for small file blocks). ---- # zfs set special_small_blocks=0 / ---- + +[[sysadmin_zfs_features]] +ZFS Pool Features +~~~~~~~~~~~~~~~~~ + +Changes to the on-disk format in ZFS are only made between major version changes +and are specified through *features*. All features, as well as the general +mechanism are well documented in the `zpool-features(5)` manpage. + +Since enabling new features can render a pool not importable by an older version +of ZFS, this needs to be done actively by the administrator, by running +`zpool upgrade` on the pool (see the `zpool-upgrade(8)` manpage). + +Unless you need to use one of the new features, there is no upside to enabling +them. + +In fact, there are some downsides to enabling new features: + +* A system with root on ZFS, that still boots using `grub` will become + unbootable if a new feature is active on the rpool, due to the incompatible + implementation of ZFS in grub. +* The system will not be able to import any upgraded pool when booted with an + older kernel, which still ships with the old ZFS modules. +* Booting an older {pve} ISO to repair a non-booting system will likewise not + work. + +IMPORTANT: Do *not* upgrade your rpool if your system is still booted with +`grub`, as this will render your system unbootable. This includes systems +installed before {pve} 5.4, and systems booting with legacy BIOS boot (see +xref:sysboot_determine_bootloader_used[how to determine the bootloader]). + +.Enable new features for a ZFS pool: +---- +# zpool upgrade +----