X-Git-Url: https://git.proxmox.com/?p=pve-docs.git;a=blobdiff_plain;f=local-zfs.adoc;h=5cce6778bd81dafa800e456a9bb1e8613c78a338;hp=6aae81e4a275c729a86514fd2b2d1b5321dcb59b;hb=cc38b9254cf54f33b3cd4c247ee273c1ddad146f;hpb=b2f242abe4c50227f5610767e6fcaa40654c2b88 diff --git a/local-zfs.adoc b/local-zfs.adoc index 6aae81e..5cce677 100644 --- a/local-zfs.adoc +++ b/local-zfs.adoc @@ -1,6 +1,6 @@ +[[chapter_zfs]] ZFS on Linux ------------ -include::attributes.txt[] ifdef::wiki[] :pve-toplevel: endif::wiki[] @@ -60,7 +60,7 @@ 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 data corruption, we recommend the use of high quality ECC RAM. -If you use a dedicated cache and/or log disk, you should use a +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 increase the overall performance significantly. @@ -154,15 +154,9 @@ rpool/swap 4.25G 7.69T 64K - Bootloader ~~~~~~~~~~ -The default ZFS disk partitioning scheme does not use the first 2048 -sectors. This gives enough room to install a GRUB boot partition. The -{pve} installer automatically allocates that space, and installs the -GRUB boot loader there. If you use a redundant RAID setup, it installs -the boot loader on all disk required for booting. So you can boot -even if some disks fail. - -NOTE: It is not possible to use ZFS as root file system with UEFI -boot. +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. ZFS Administration @@ -184,41 +178,55 @@ 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 +---- +# zpool create -f -o ashift=12 +---- -To activate compression +To activate compression (see section <>): - zfs set compression=lz4 +---- +# zfs set compression=lz4 +---- .Create a new pool with RAID-0 -Minimum 1 Disk +Minimum 1 disk - zpool create -f -o ashift=12 +---- +# zpool create -f -o ashift=12 +---- .Create a new pool with RAID-1 -Minimum 2 Disks +Minimum 2 disks - zpool create -f -o ashift=12 mirror +---- +# zpool create -f -o ashift=12 mirror +---- .Create a new pool with RAID-10 -Minimum 4 Disks +Minimum 4 disks - zpool create -f -o ashift=12 mirror mirror +---- +# zpool create -f -o ashift=12 mirror mirror +---- .Create a new pool with RAIDZ-1 -Minimum 3 Disks +Minimum 3 disks - zpool create -f -o ashift=12 raidz1 +---- +# zpool create -f -o ashift=12 raidz1 +---- .Create a new pool with RAIDZ-2 -Minimum 4 Disks +Minimum 4 disks - zpool create -f -o ashift=12 raidz2 +---- +# zpool create -f -o ashift=12 raidz2 +---- .Create a new pool with cache (L2ARC) @@ -228,7 +236,9 @@ the performance (use SSD). As `` it is possible to use more devices, like it's shown in "Create a new pool with RAID*". - zpool create -f -o ashift=12 cache +---- +# zpool create -f -o ashift=12 cache +---- .Create a new pool with log (ZIL) @@ -238,11 +248,13 @@ the performance(SSD). As `` it is possible to use more devices, like it's shown in "Create a new pool with RAID*". - zpool create -f -o ashift=12 log +---- +# zpool create -f -o ashift=12 log +---- .Add cache and log to an existing pool -If you have an pool without cache and log. First partition the SSD in +If you have a pool without cache and log. First partition the SSD in 2 partition with `parted` or `gdisk` IMPORTANT: Always use GPT partition tables. @@ -251,11 +263,29 @@ The maximum size of a log device should be about half the size of physical memory, so this is usually quite small. The rest of the SSD can be used as cache. - zpool add -f log cache +---- +# zpool add -f log cache +---- .Changing a failed device - zpool replace -f +---- +# zpool replace -f +---- + +.Changing a failed bootable device when using systemd-boot + +---- +# sgdisk -R +# sgdisk -G +# zpool replace -f +# pve-efiboot-tool format +# pve-efiboot-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]. Activate E-Mail Notification @@ -263,7 +293,12 @@ 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. +pool errors. Newer ZFS packages ship the daemon in a separate package, +and you can install it using `apt-get`: + +---- +# apt-get install zfs-zed +---- 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: @@ -298,21 +333,30 @@ This example setting limits the usage to 8GB. If your root file system is ZFS you must update your initramfs every time this value changes: - update-initramfs -u +---- +# update-initramfs -u +---- ==== -.SWAP on ZFS +[[zfs_swap]] +SWAP on ZFS +~~~~~~~~~~~ -SWAP on ZFS on Linux may generate some troubles, like blocking the +Swap-space created on a zvol may generate some troubles, like blocking the server or generating a high IO load, often seen when starting a Backup to an external Storage. We strongly recommend to use enough memory, so that you normally do not -run into low memory situations. Additionally, you can lower the +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. +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: - 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: @@ -334,3 +378,176 @@ improve performance when sufficient memory exists in a system. | vm.swappiness = 60 | The default value. | vm.swappiness = 100 | The kernel will swap aggressively. |=========================================================== + +[[zfs_encryption]] +Encrypted ZFS Datasets +~~~~~~~~~~~~~~~~~~~~~~ + +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: + +---- +# zpool get feature@encryption tank +NAME PROPERTY VALUE SOURCE +tank feature@encryption disabled local + +# zpool set feature@encryption=enabled + +# zpool get feature@encryption tank +NAME PROPERTY VALUE SOURCE +tank feature@encryption enabled local +---- + +WARNING: There is currently no support for booting from pools with encrypted +datasets using Grub, and only limited support for automatically unlocking +encrypted datasets on boot. Older versions of ZFS without encryption support +will not be able to decrypt stored data. + +NOTE: It is recommended to either unlock storage datasets manually after +booting, or to write a custom unit to pass the key material needed for +unlocking on boot to `zfs load-key`. + +WARNING: Establish and test a backup procedure before enabling encryption of +production data. If the associated key material/passphrase/keyfile has been +lost, accessing the encrypted data is no longer possible. + +Encryption needs to be setup when creating datasets/zvols, and is inherited by +default to child datasets. For example, to create an encrypted dataset +`tank/encrypted_data` and configure it as storage in {pve}, run the following +commands: + +---- +# zfs create -o encryption=on -o keyformat=passphrase tank/encrypted_data +Enter passphrase: +Re-enter passphrase: + +# pvesm add zfspool encrypted_zfs -pool tank/encrypted_data +---- + +All guest volumes/disks create on this storage will be encrypted with the +shared key material of the parent dataset. + +To actually use the storage, the associated key material needs to be loaded +with `zfs load-key`: + +---- +# zfs load-key tank/encrypted_data +Enter passphrase for 'tank/encrypted_data': +---- + +It is also possible to use a (random) keyfile instead of prompting for a +passphrase by setting the `keylocation` and `keyformat` properties, either at +creation time or with `zfs change-key` on existing datasets: + +---- +# dd if=/dev/urandom of=/path/to/keyfile bs=32 count=1 + +# zfs change-key -o keyformat=raw -o keylocation=file:///path/to/keyfile tank/encrypted_data +---- + +WARNING: When using a keyfile, special care needs to be taken to secure the +keyfile against unauthorized access or accidental loss. Without the keyfile, it +is not possible to access the plaintext data! + +A guest volume created underneath an encrypted dataset will have its +`encryptionroot` property set accordingly. The key material only needs to be +loaded once per encryptionroot to be available to all encrypted datasets +underneath it. + +See the `encryptionroot`, `encryption`, `keylocation`, `keyformat` and +`keystatus` properties, the `zfs load-key`, `zfs unload-key` and `zfs +change-key` commands and the `Encryption` section from `man zfs` for more +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= +---- + +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 +---- + +Again, only new blocks will be affected by this change. + + +ZFS Special Device +~~~~~~~~~~~~~~~~~~ + +Since version 0.8.0 ZFS supports `special` devices. A `special` device in a +pool is used to store metadata, deduplication tables, and optionally small +file blocks. + +A `special` device can improve the speed of a pool consisting of slow spinning +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. + +WARNING: Adding a `special` device to a pool cannot be undone! + +.Create a pool with `special` device and RAID-1: + +---- +# zpool create -f -o ashift=12 mirror special mirror +---- + +.Add a `special` device to an existing pool with RAID-1: + +---- +# zpool add special mirror +---- + +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 +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` (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 all file smaller than 4K-blocks pool-wide: + +---- +# zfs set special_small_blocks=4K +---- + +.Opt in for small file blocks for a single dataset: + +---- +# zfs set special_small_blocks=4K / +---- + +.Opt out from small file blocks for a single dataset: + +---- +# zfs set special_small_blocks=0 / +----