System updates without worries thanks to Btrfs snapshots and Snapper - TUXEDO Computers

Anyone who uses Linux regularly is familiar with that uneasy feeling before major system updates, especially as a beginner. In the vast majority of cases, updates go smoothly. Still, some residual risk remains: a faulty package, an unfortunate configuration change, or an incompatibility between components can cause the system to no longer start as usual afterward, or individual functions to fail.

Until now, such situations often meant tedious troubleshooting or, in the worst case, a complete reinstallation of the system. With the new foundation of TUXEDO OS, this scenario is largely a thing of the past. The key to this is the switch to the modern copy-on-write file system Btrfs in combination with Snapper.

What Does Btrfs Do Differently?

Unlike classic Linux file systems such as ext4, Btrfs can create so-called snapshots. These aren’t complete copies of the system, but rather snapshots of the file system’s state. Thanks to the copy-on-write principle, no data is duplicated at first. Only once files change after the snapshot does Btrfs store the differences. This means snapshots are created within seconds and require comparatively little additional storage space—making them ideal for capturing the state of the system before potentially critical changes.

How Much Storage Do Snapshots Require?

A common concern relates to the additional storage requirements. In fact, Btrfs snapshots are considerably more space-efficient than many users expect. Since Btrfs works on the copy-on-write principle, no files are copied when a snapshot is created. The snapshot simply references the data blocks that already exist. Only when files are later modified does the file system allocate new blocks and store just those differences.

The actual storage consumption therefore depends on how many changes occur between two snapshots. A freshly created snapshot requires almost no additional space, while extensive system updates or numerous package installations can increase the storage requirement accordingly.

To keep available storage from growing uncontrollably, Snapper manages the snapshots automatically, following either distributor-defined or self-defined retention rules. Older restore points are deleted once they’re no longer needed. Users therefore normally don’t need to worry about either the number of snapshots or their storage consumption, though they can configure this themselves if desired.

Automatic Snapshots Before Every Update

In TUXEDO OS, Snapper, a tool that has been developed at openSUSE since 2011, works together with Btrfs in the background. Before the package manager introduces changes to the system, Snapper automatically creates a snapshot of the current state. Only after that does the actual installation of updates begin. A further snapshot is created after the update.

The entire process runs fully automatically. Users don’t need to create a snapshot themselves, nor do they need to remember to back up the system before a major update. If the update completes successfully, the snapshot initially remains on the system and can later be cleaned up automatically. If problems occur, however, a consistent system state is available at all times. Users can also manually create a snapshot before making manual configuration changes and roll that back if needed too.

When Something Does Go Wrong

Rolling back to a working snapshot works as follows: You install the latest system updates as usual. Among them is a new version of the graphics stack. After rebooting, Plasma still starts, but the screen stays black or gets stuck in a login loop. In the past, this is where the troubleshooting would begin via a TTY console, live systems, or rescue media.

With Btrfs and Snapper, the process looks much simpler. A snapshot was automatically created before the update. This previous system state can be selected and booted via the bootloader. If everything works as expected there, the system can then be reset to this snapshot.

Within just a few minutes, the operating system is back in exactly the state it was in immediately before the faulty update. This not only significantly reduces downtime; it also removes a large part of the risk that comes with updates.

Btrfs Assistant: Managing Snapshots Conveniently

Anyone who wants a look behind the scenes will find Btrfs Assistant in TUXEDO OS,  a modern graphical interface for managing Btrfs snapshots. The application displays all automatically created restore points clearly and lets you browse the snapshots, check their storage requirements, or prepare a rollback if needed.

Beyond that, Btrfs Assistant bundles numerous diagnostic and management functions related to the file system. For example, you can check the file system’s health, trigger maintenance tasks, or retrieve information about Subvolumes and snapshots, all conveniently through a graphical interface. System maintenance tasks such as scrub and balance can also be triggered from there. Advanced users thus get a powerful tool, while less experienced users generally don’t need to intervene at all in everyday use, since snapshots and their management happen automatically.

No Substitute for Backups

Snapshots are often confused with backups. In fact, the two serve different purposes. A snapshot protects the installed operating system against unwanted changes and enables a quick return to a working state. However, it resides on the same disk as the original system. Against hardware failures or the loss of a storage medium, classic backups to an external medium and, to be safe, a different location, remain essential.

For everyday use, though, snapshots represent an enormous gain in security. They catch exactly the problems that occur most often in daily operation: failed updates, faulty configuration changes, or botched experiments with system components.

More Freedom to Experiment

Linux, in particular, thrives on trying new things. New desktop versions, alternative drivers, or additional software can now be tested much more relaxedly. Should a change have unexpected side effects, a rollback to the last working snapshot is enough. Instead of hours of troubleshooting or a complete reinstallation, the system is ready for use again within a very short time.

With the combination of Debian as the new base, Btrfs as the standard file system, Snapper for automatic snapshots, and Btrfs Assistant as a convenient management interface, TUXEDO OS offers an additional layer of protection against faulty packages and user misconfiguration. At the appropriate time, we’ll explain in a dedicated article how to work safely with snapshots.

The Following Articles Have Been Published in This Series So Far:

• A New Foundation for TUXEDO OS: The Switch to Debian
• Security Under TUXEDO OS: How We Secure Debian Testing
• How Things Continue with TUXEDO OS, Ubuntu, and Kubuntu