General Backup Formatting Info

General Discussion
1

Heading down the backup road with Qubes. Can someone advise if the target needs to be formatted?

If yes, which formatting would be best for backup.

If it doesn’t need to be formatted does Qubes format the entire target and remove any existing data?

Thanks.

2

The backup tool generates a flat file. You can store it wherever you want. There are no specific guidelines for the filesystem.

3

The backup generates a single file as Solene mentioned earlier. And yes, the target has tbe formatted and mounted. The only consideration is that the target file system should support huge backup files (unless you are doing a partial backup). And it should be taken into consideration that if the target is formatted as FAT32 (like many flash drives), it will have a 4GiB limit of a single file. And full backup will most probably fail.

4

That’s why I always format my data flash drive as ExFAT

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5

The medium needs to be formatted - Qubes will not automatically format
or remove data.
As pointed out, the medium (whether external or in a qube) needs to be
formatted and mounted ,and the target location needs to be writable by the user account.

I never presume to speak for the Qubes team.
When I comment in the Forum I speak for myself.

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6

Thanks

7

Welcome! To answer your question- No, the Qubes backup tool won’t format your entire drive; it just saves the backup as a single large file (or a set of files) in whatever folder you choose. As for formatting, ext4 is usually the safest bet for Linux. If you ever think you’ll need to grab a file from a Windows machine, you could use exFAT, but ext4 is definitely the native ‘it just works’ choice for Qubes.

8

Great choice going with Qubes for backups — it’s a solid system once you get the hang of it.

Does the target need to be formatted?

No, the target does not need to be pre-formatted in any special way. Qubes backup writes a single encrypted archive file (or a set of split files) to the destination, so it just needs a writable location — a mounted drive, a directory, or even a remote destination via SSH.

What filesystem should the target use?

That said, filesystem choice does matter practically:

  • ext4 is the most reliable and recommended option if the target is a dedicated Linux drive. No file size limitations that would interfere with large backups.
  • exFAT or NTFS can work if you need cross-platform compatibility (e.g., also accessing the drive on Windows), but be aware that Qubes backup can produce very large files, and FAT32 is a hard no due to its 4 GB file size limit.
  • Btrfs works fine too if you’re already using it.

The main thing to avoid is FAT32 — the 4 GB cap will cause the backup to fail if any single chunk exceeds that.

Does Qubes wipe or reformat the target?

No. Qubes does not format the target drive or remove existing data. It simply writes the backup archive into the directory you specify. Any existing files on the drive are left untouched. You’re responsible for managing the space yourself, so make sure there’s enough free space before starting.

One practical tip: Qubes backup files are already AES-256 encrypted, so you don’t necessarily need an encrypted filesystem on the target — the backup itself is protected. That said, using an encrypted drive (e.g., LUKS on Linux) adds a nice extra layer, especially if the drive could be physically lost or stolen.