FAQ: ZoL->OpenZFS conversions
Signed-off-by: George Melikov <mail@gmelikov.ru>
This commit is contained in:
George Melikov
@@ -4,12 +4,10 @@ FAQ
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.. contents:: Table of Contents
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:local:
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What is ZFS on Linux
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--------------------
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What is OpenZFS
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---------------
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The ZFS on Linux project is an implementation of
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`OpenZFS <https://openzfs.org/wiki/Main_Page>`__ designed to work in a
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Linux environment. OpenZFS is an outstanding storage platform that
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OpenZFS is an outstanding storage platform that
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encompasses the functionality of traditional filesystems, volume
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managers, and more, with consistent reliability, functionality and
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performance across all distributions. Additional information about
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@@ -53,23 +51,23 @@ requires.
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Installation
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------------
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ZFS on Linux is available for all major Linux distributions. Refer to
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the :doc:`getting started <../Getting Started/index>` section of the wiki for links to installations
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instructions for many popular distributions. If your distribution isn't
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listed you can always build ZFS on Linux from the latest official
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`tarball <https://github.com/zfsonlinux/zfs/releases>`__.
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OpenZFS is available for FreeBSD and all major Linux distributions. Refer to
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the :doc:`getting started <../Getting Started/index>` section of the wiki for
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links to installations instructions. If your distribution/OS isn't
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listed you can always build OpenZFS from the latest official
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`tarball <https://github.com/openzfs/zfs/releases>`__.
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Supported Architectures
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-----------------------
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ZFS on Linux is regularly compiled for the following architectures:
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x86_64, x86, aarch64, arm, ppc64, ppc.
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OpenZFS is regularly compiled for the following architectures:
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aarch64, arm, ppc, ppc64, x86, x86_64.
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Supported Kernels
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-----------------
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Supported Linux Kernels
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-----------------------
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The `notes <https://github.com/zfsonlinux/zfs/releases>`__ for a given
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ZFS on Linux release will include a range of supported kernels. Point
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The `notes <https://github.com/openzfs/zfs/releases>`__ for a given
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OpenZFS release will include a range of supported kernels. Point
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releases will be tagged as needed in order to support the *stable*
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kernel available from `kernel.org <https://www.kernel.org/>`__. The
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oldest supported kernel is 2.6.32 due to its prominence in Enterprise
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@@ -80,11 +78,11 @@ Linux distributions.
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32-bit vs 64-bit Systems
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------------------------
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You are **strongly** encouraged to use a 64-bit kernel. ZFS on Linux
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will build for 32-bit kernels but you may encounter stability problems.
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You are **strongly** encouraged to use a 64-bit kernel. OpenZFS
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will build for 32-bit systems but you may encounter stability problems.
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ZFS was originally developed for the Solaris kernel which differs from
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the Linux kernel in several significant ways. Perhaps most importantly
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some OpenZFS platforms in several significant ways. Perhaps most importantly
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for ZFS it is common practice in the Solaris kernel to make heavy use of
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the virtual address space. However, use of the virtual address space is
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strongly discouraged in the Linux kernel. This is particularly true on
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@@ -118,8 +116,10 @@ excellent walk throughs available for
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:doc:`Ubuntu <../Getting Started/Ubuntu/index>`, and
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`Gentoo <https://github.com/pendor/gentoo-zfs-install/tree/master/install>`__.
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Selecting /dev/ names when creating a pool
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------------------------------------------
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On FreeBSD 13+ booting from ZFS is supported out of the box.
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Selecting /dev/ names when creating a pool (Linux)
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--------------------------------------------------
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There are different /dev/ names that can be used when creating a ZFS
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pool. Each option has advantages and drawbacks, the right choice for
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@@ -485,10 +485,7 @@ Performance Considerations
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--------------------------
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To achieve good performance with your pool there are some easy best
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practices you should follow. Additionally, it should be made clear that
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the ZFS on Linux implementation has not yet been optimized for
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performance. As the project matures we can expect performance to
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improve.
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practices you should follow.
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- **Evenly balance your disk across controllers:** Often the limiting
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factor for performance is not the disk but the controller. By
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@@ -559,16 +556,17 @@ ZVOL used space larger than expected
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snapshot the zvol, as the space referenced by the snapshots will
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contain the unused blocks.
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| This issue can be prevented, by using the ``fstrim`` command to allow
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| This issue can be prevented, by issuing the so-called trim
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(for ex. ``fstrim`` command on Linux) to allow
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the kernel to specify to zfs which blocks are unused.
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| Executing a ``fstrim`` command before a snapshot is taken will ensure
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| Issuing a trim before a snapshot is taken will ensure
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a minimum snapshot size.
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| Adding the ``discard`` option for the mounted ZVOL in ``/etc/fstab``
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effectively enables the Linux kernel to issue the trim commands
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| For Linux adding the ``discard`` option for the mounted ZVOL in ``/etc/fstab``
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effectively enables the kernel to issue the trim commands
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continuously, without the need to execute fstrim on-demand.
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Using a zvol for a swap device
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------------------------------
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Using a zvol for a swap device on Linux
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---------------------------------------
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You may use a zvol as a swap device but you'll need to configure it
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appropriately.
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@@ -594,12 +592,12 @@ please send your logs
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-o primarycache=metadata \
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-o com.sun:auto-snapshot=false rpool/swap
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Using ZFS on Xen Hypervisor or Xen Dom0
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---------------------------------------
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Using ZFS on Xen Hypervisor or Xen Dom0 (Linux)
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-----------------------------------------------
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It is usually recommended to keep virtual machine storage and hypervisor
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pools, quite separate. Although few people have managed to successfully
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deploy and run ZFS on Linux using the same machine configured as Dom0.
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deploy and run OpenZFS using the same machine configured as Dom0.
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There are few caveats:
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- Set a fair amount of memory in grub.conf, dedicated to Dom0.
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@@ -616,8 +614,8 @@ There are few caveats:
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one <https://github.com/zfsonlinux/zfs/issues/1067>`__ related to
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ballooning
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udisks2 creating /dev/mapper/ entries for zvol
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----------------------------------------------
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udisks2 creating /dev/mapper/ entries for zvol (Linux)
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------------------------------------------------------
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To prevent udisks2 from creating /dev/mapper entries that must be
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manually removed or maintained during zvol remove / rename, create a
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@@ -696,8 +694,8 @@ to get it resolved. They may ask for information like:
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- Stack traces which may be logged to ``dmesg``.
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Does ZFS on Linux have a Code of Conduct?
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-----------------------------------------
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Does OpenZFS have a Code of Conduct?
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------------------------------------
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Yes, the ZFS on Linux community has a code of conduct. See the `Code of
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Yes, the OpenZFS community has a code of conduct. See the `Code of
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Conduct <https://openzfs.org/wiki/Code_of_Conduct>`__ for details.
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