borgbackup/borg

File systems
~~~~~~~~~~~~

We strongly recommend against using Borg (or any other database-like
software) on non-journaling file systems like FAT, since it is not
possible to assume any consistency in case of power failures (or a
sudden disconnect of an external drive or similar failures).

While Borg uses a data store that is resilient against these failures
when used on journaling file systems, it is not possible to guarantee
this with some hardware -- independent of the software used. We don't
know a list of affected hardware.

If you are suspicious whether your Borg repository is still consistent
and readable after one of the failures mentioned above occurred, run
``borg check --verify-data`` to make sure it is consistent.

.. rubric:: Requirements for Borg repository file systems

- Long file names
- At least three directory levels with short names
- Typically, file sizes up to a few hundred MB.
  Large repositories may require large files (>2 GB).
- Up to 1000 files per directory.
- rename(2) / MoveFile(Ex) should work as specified, i.e. on the same file system
  it should be a move (not a copy) operation, and in case of a directory
  it should fail if the destination exists and is not an empty directory,
  since this is used for locking.
- Also hardlinks are used for more safe and secure file updating (e.g. of the repo
  config file), but the code tries to work also if hardlinks are not supported.