Encrypted ZFS with Ubuntu

The ZFS filesystem [1] was developed by Sun Microsystems and released as open source to the public in November 2005 as part of OpenSolaris. Then, as now, it offers features not found in other filesystems. One of the main design aims was to make it as robust and reliable as possible. ZFS stores not only the data but also cryptographic checksums of the data, which allow it to identify data that has been altered because of bit-rot, power failures, or people playing with magnets. Today, after years of development, improvements, and additional features, there is hardly anything ZFS does not do.

Although many features, such as support for various RAID modes, hot-swapping of disks and very large limits on data size, number of files and similar attributes, are geared toward the enterprise user, plenty of others will be of interest to home users. For example, ZFS supports transparent compression, with a choice of different compression algorithms and levels. Data can be de-duplicated automatically, making all those backup copies less space-consuming. Speaking of backups, ZFS supports block-level snapshots that only consume space when files actually change as well as the ability to send and receive those snapshots as filesystem streams over the network. Anybody who has had to run rsync on large numbers of files will appreciate the performance improvement that this brings.

Although ZFS has been the main filesystem on OpenSolaris since 2005 and has been fully supported on FreeBSD and other BSDs for several years, its adoption by the Linux community [2] has been somewhat slower, not because of lack of enthusiasm, but rather because of legal issues. ZFS was released under the Common Development and Distribution License (CDDL). This license is not compatible with the GPL, meaning that ZFS cannot be bundled with the Linux kernel. One way around this restriction was to implement ZFS support through a Filesystem in Userspace (FUSE) module.This approach comes with a number of limitations, most notably, a significant performance penalty is incurred for running through FUSE, and ZFS cannot be used as a root filesystem.

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