ZFS Update

Newer versions of ZFS resolve bugs, add support for newer kernels, and in some instances, introduce new storage pool features.

Portage will update these packages in the normal fashion through emerge --update @world. Special attention should be given when Funtoo Linux is installed onto ZFS: that is root (/) resides in a storage pool. Important additional steps are recommended.

* The ZFS ebuilds are sys-fs/zfs, sys-fs/zfs-kmod and sys-kernel/spl.

   Important

As best practice, it is strongly recommended that all users backup their data on a regular basis - irrespective of the file system being used. This could be particularly important should something go wrong while modifying or updating a live file system.

Funtoo installed on ZFS

Following updates to ZFS packages, the initramfs responsible for importing and mounting root (/) should be updated prior to rebooting. By having an initramfs with the same (version) ZFS executables (zpool, zfs) as found in /sbin, the likelihood of a boot failure is reduced.

Do note that updating initramfs may also require the updating of bootloader or UEFI configuration as well.

...with GRUB

GRUB can support /boot residing within a ZFS storage pool (together with root /). There is an official installation guide for this configuration: ZFS Install Guide.

Old versions of GRUB may not be able to re-import your root pool if the new ZFS features have been enabled. To reduce the likelihood of boot failure, GRUB should also be updated together with initramfs before enabling new storage pool features.

Updating from old versions of ZFS (0.6.3 or older) will introduce new storage pool features. After updating ZFS, a review of the pool status will indicate that new features are available.

root # zpool status
  pool: rpool
 state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
	still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
	the pool may no longer be accessible by software that does not support
	the features. See zpool-features(5) for details.
  scan: none requested
config:

	NAME                                             STATE     READ WRITE CKSUM
	rpool                                            ONLINE       0     0     0
	  ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF  ONLINE       0     0     0

errors: No known data errors

The recommended steps to take before enabling new storage pool features are:

1. For now, ignore the option to upgrade the storage pool rpool.
2. Update your initramfs to include the latest ZFS binary executables.
3. If possible upgrade No results to the latest version (2.0.2). Follow Install for GRUB installation instructions, including grub-install.
4. Confirm that your system reboots successfully. That is, mounting the root pool rpool.
5. (Optional) Upgrade your storage pool to enable new features.

Updating Storage Pool Features

Without specifying a pool name the command zpool upgrade will indicate pools available for upgrade.

root # zpool upgrade
This system supports ZFS pool feature flags.

All pools are formatted using feature flags.


Some supported features are not enabled on the following pools. Once a
feature is enabled the pool may become incompatible with software
that does not support the feature. See zpool-features(5) for details.

POOL  FEATURE
---------------
rpool
      async_destroy
      empty_bpobj
      lz4_compress
      spacemap_histogram
      enabled_txg
      hole_birth
      extensible_dataset
      embedded_data
      bookmarks
      filesystem_limits
      large_blocks

Updating initramfs and rebooting as described earlier. To enable all new storage pool features on rpool, issue the following command.

root # zpool upgrade rpool
This system supports ZFS pool feature flags.

Enabled the following features on 'rpool':
  async_destroy
  empty_bpobj
  lz4_compress
  spacemap_histogram
  enabled_txg
  hole_birth
  extensible_dataset
  embedded_data
  bookmarks
  filesystem_limits
  large_blocks

The previous 'status' and 'action' messages will disappear.

root # zpool status
  pool: rpool
 state: ONLINE
  scan: none requested
config:

	NAME                                             STATE     READ WRITE CKSUM
	rpool                                            ONLINE       0     0     0
	  ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF  ONLINE       0     0     0

errors: No known data errors