Frequently asked questions

Which platforms are supported?

Currently Linux, FreeBSD and MacOS X are supported.

Can I backup VM disk images?

Yes, the deduplication technique used by Attic makes sure only the modified parts of the file are stored.

Which file attributes are preserved?

The following attributes are preserved:

• Name
• Contents
• Time of last modification (nanosecond precision with Python >= 3.3)
• User ID of owner
• Group ID of owner
• Unix Permission
• Extended attributes (xattrs)
• Access Control Lists (ACL) on Linux, OS X and FreeBSD
• BSD flags on OS X and FreeBSD

How can I specify the encryption passphrase programmatically?

The encryption passphrase can be specified programmatically using the ATTIC_PASSPHRASE environment variable. This is convenient when setting up automated encrypted backups. Another option is to use key file based encryption with a blank passphrase. See Repository encryption for more details.

When backing up to remote servers, is data encrypted before leaving the local machine, or do I have to trust that the remote server isn’t malicious?

Yes, everything is encrypted before leaving the local machine.

If a backup stops mid-way, does the already-backed-up data stay there? I.e. does Attic resume backups?

Yes, during a backup a special checkpoint archive named <archive-name>.checkpoint is saved every 5 minutes containing all the data backed-up until that point. This means that at most 5 minutes worth of data needs to be retransmitted if a backup needs to be restarted.