Installing & using ZFS on Ubuntu

Get zFS

sudo apt-add-repository --yes ppa:zfs-native/stable
sudo apt-get update
sudo apt-get install --yes ubuntu-zfs
echo done

General information

ZFS filesystems are built on top of virtual storage pools called zpools. A zpool is constructed of virtual devices (vdevs), which are themselves constructed of block devices: files, hard drive partitions, or entire drives, with the last being the recommended usage.[6] Block devices within a vdev may be configured in different ways, depending on needs and space available: non-redundantly (similar to RAID 0), as a mirror (RAID 1) of two or more devices, as a RAID-Z group of three or more devices, or as a RAID-Z2 group of four or more devices.[7] Besides standard storage, devices can be designated as volatile read cache (ARC), nonvolatile write cache, or as a spare disk for use only in the case of a failure. Finally, when mirroring, block devices can be grouped according to physical chassis, so that the filesystem can continue in the face of the failure of an entire chassis. -

First step - zpool

zpool create [poolName] mirror /dev/disk/by-id/scsi-SATA_[id1] /dev/disk/by-id/scsi-SATA_[id2]
Always use the long `/dev/disk/by-id/*` aliases with ZFS. Using the `/dev/sd*` device nodes directly can cause sporadic import failures, especially on systems that have more than one storage pool. > [...] > The pool name is arbitrary. On systems that can automatically install to ZFS, the root pool is named "rpool" by default. Note that system recovery is easier if you choose a unique name instead of "rpool". Anything except "rpool" or "tank", like the hostname, would be a good choice. -

zfs / mounting

Creating filesystems

The zfs command configures ZFS datasets within a ZFS storage pool, as described in zpool(1M). A dataset is identified by a unique path within the ZFS namespace. For example: [poolName]/{filesystem,volume,snapshot}
A ZFS dataset of type filesystem can be mounted within the standard system namespace and behaves like other file systems. While ZFS file systems are designed to be POSIX compliant, known issues exist that prevent compliance in some cases. Applications that depend on standards conformance might fail due to nonstandard behavior when checking file system free space.
The following commands create a file system named pool/home and a file system named pool/home/bob. The mount point /export/home is set for the parent file system, and is automatically inherited by the child file system.
zfs create <poolName>/home
zfs create [poolName]/home/bob

Mounting filesystems

[...] ZFS automatically manages mounting and unmounting file systems without the need to edit the /etc/vfstab file. All automatically managed file systems are mounted by ZFS at boot time. By default, file systems are mounted under /path, where path is the name of the file system in the ZFS namespace. Directories are created and destroyed as needed. A file system can also have a mount point set in the mountpoint property. This directory is created as needed, and ZFS automatically mounts the file system when the `zfs mount -a` command is invoked (without editing /etc/vfstab). The mountpoint property can be inherited, so if pool/home has a mount point of /export/stuff, then pool/home/user automatically inherits a mount point of /export/stuff/user.
zfs set mountpoint=/export/home [poolName]/home
zfs mount -a
A file system mountpoint property of none prevents the file system from being mounted. If needed, ZFS file systems can also be managed with traditional tools (mount, umount, /etc/vfstab). If a file system's mount point is set to legacy, ZFS makes no attempt to manage the file system, and the administrator is responsible for mounting and unmounting the file system. -
The author

Written by Per

Free software enthusiast and transhumanist residing in Stuttgart, Germany.

comments powered by Disqus