BTRFS As a Filesystem For The Backup Disc?

1

I’m thinking about BTRFS as the filesystem for a new local backup disc. However, I’m not sure if it really makes sense:

  • Encryption:
    Duplicati can do it. BTRFS cannot. But the kernel can do it on an even lower level, for ex. via Luks. I think Luks will be the fastest / most flexible solution. Correct?

  • Compression:
    Duplicati can do it. BTRFS can do it, too. In contrast to BTRFS, Duplicati can recognize if it doesn’t make sense to compress a file. So it’s better to use the Duplicati compression than the BTRFS one. Correct?

  • Snapshots:
    BTRFS snapshots don’t make sense here. Correct?

  • Subvolumes:
    BTRFS subvolumes aren’t needed in the use case of Duplicati. Correct?

  • Raid:
    Imho, the BTRFS Raid features also don’t make sense on a backup disc. So the BTRFS filesystem should be a “single” filesystem. Correct?

  • Disc Read Errors:
    BTRFS can detect and sometimes even autocorrect disc read errors. This could be a huge advantage compared to other filesystems. Does Duplicati have a similar feature?

  • CoW:
    BTRFS can do data-CoW. Does BTRFS CoW make sense on a disc partition where only Duplicati backups are stored?

Do there exist further advantages / disadvantages / pitfalls for BTRFS versus more traditional filesystems like EXT4?

2

On my home machines, Duplicati backs up to my NAS which uses btrfs.

I think snapshots are useful to protect your backup data from accidental or intentional damage (by ransomware for instance). My NAS automatically takes snapshots and deletes them after a certain time period.

Also I think its ability to detect and recover from “bitrot” is beneficial (Duplicati itself has no integrated ability to heal from such errors, although some initial effort was made to implement it.)

Its other filesystem features are probably of little value to Duplicati, but they don’t hurt anything.

1 Like