Snapshots with Btrfs

In the release notes, SUSE conscientiously points out that SLE differs from its predecessor in several fundamental ways: the filesystem is the first. SLE comes with Btrfs as the default for the root filesystem, making SLE the first major Linux distribution to rely on Btrfs.

SUSE makes it clear that its support for Btrfs is not a PR stunt. SUSE has deployed some development resources in recent years to meaningfully integrate Btrfs with SLE. This effort gave rise to tools such as Snapper [5], a smart tool used to create snapshots across the entire filesystem. (Btrfs's built-in support for snapshots makes it an ideal option for an enterprise Linux filesystem.)

Snapper gives admins the ability to create snapshots of files, folders, or the entire filesystem at will, but also to delete these snapshots or dump them in a different location as a backup. This feature can save admins much work; for example, you can easily create a snapshot of the entire filesystem via Snapper before updating the SLE 12 system. If the update proceeds without problems, admins are happy – and if the update goes wrong, they may not be happy, but at least they are not worried: Thanks to the Btrfs snapshot, you can restore the state of the system before the update at any time. Only the /boot directory is not covered by this snapshot mechanism. Currently, it is still impossible to boot from a Btrfs partition. Therefore, /boot is always on a separate partition and uses a different filesystem, which means that, to undo a full system upgrade, you might need to manually remove the installed kernel.

Welcome to Systemd!

Under the SLE-12 hood, you will find several changes that you will probably not notice at first glance. For example, the ancient System V init is no longer present. SUSE instead uses systemd – a bone of contention in the Linux world. SUSE developers wistfully refer to System V as old and venerable in the 12 changelog, but whether admins will mourn the old dog is doubtful. SLE 12 boots much faster compared to the previous version, because it can perform various operations in parallel.

Not Broken: the Wicked Network Manager

In the wake of the systemd change, SLE introduces 12 additional innovations; one example is the new Wicked network manager [6] (Figures 7 and 8).

Figure 7: Although the network configuration looks like business as usual in YaST, a quick glance at the process table shows that …

Figure 8: … the new Wicked network manager handles the network configuration work.

Wicked is an in-house development, which was initially tested in openSUSE, and which SUSE now considers mature enough for production work in the enterprise. On the surface, everything is the same: as in older versions, you still configure the network with YaST, and you can continue to use your existing configuration files from older SUSE systems without any restriction. However, if you want to look into the network configuration beyond YaST, you need to rethink. Wicked is deeply integrated with the D-Bus messaging system and comes with its own command-line tool.

The question is whether SUSE is doing itself a favor with Wicked – hardcore admins don't typically appreciate new tools that perform provide basic tasks with a higher-than-necessary level of complexity.