The professional filesystem ZFS

Snapshots

Another common technique for enhancing the data security of a filesystem is creating snapshots. ZFS provides very easy and efficient snapshot capability thanks to its copy-on-write technology; older data is always saved, because the filesystem stores new datasets in free memory blocks instead of overwriting the existing data. The following command creates snapshots of a volume:

# zfs snapshot pool_name/volume@snapshot_name

The system creates the snapshot in the current directory in a hidden folder with the extension .zfs. Although this folder is not displayed with the ls -lisa command, you can change to it with a simple cd .zfs. This .zfs directory has a snapshot/ subfolder, where you will find your snapshot(s).

The individual snapshots are accessible as in conventional file hierarchies: You can retrieve or copy files from them, and you can create backups. The snapshot technology built into ZFS is far more flexible than you will find in other filesystems (Figure 4).

Figure 4: Create and access ZFS snapshots from a terminal window.

Conclusions

ZFS is one of the most innovative and modern filesystems available for Unix-flavored operating systems today. Restrictions of obsolete filesystems fall away completely with ZFS, and ZFS comes with a range of features, such as RAID, snapshots, and data compression. ZFS also cuts a good figure on the desktop. The less sophisticated Btrfs provides some of the enhanced features of ZFS, but Btrfs has its own issues. It is time to resolve the restrictive license disputes around ZFS and make the ZFS filesystem fully suitable for use on Linux.

Infos

  1. ZFS: http://docs.oracle.com/cd/E19253-01/819-5461/zfsover-2/
  2. Common Development and Distribution License: https://opensource.org/licenses/CDDL-1.0
  3. Filesystem in User Space (FUSE): https://en.wikipedia.org/wiki/Filesystem_in_Userspace
  4. Storage pools: http://docs.oracle.com/cd/E19253-01/819-5461/gaypk/index.html
  5. ZFS on FUSE: http://zfs-on-fuse.blogspot.co.uk/
  6. ZFS on Linux: http://zfsonlinux.org/
  7. ZFS with Ubuntu: https://insights.ubuntu.com/2016/02/16/zfs-is-the-fs-for-containers-in-ubuntu-16-04/

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