• Backing up and restoring Arch archives

Backing up and restoring Arch archives

tla's facilities for mirroring archives may also be used as a reliable way of taking backups. Suppose your main development archive (foo@example.com--stuff-2004) is located at sftp://arch-server.example.com/home/arch/stuff/2004. Many developers contribute day and night to this archive[0], so there's always the risk of new revisions being committed in the middle of a backup, regardless of when you schedule your backup. You have a back-up server called vault.example.com, and wish to back up your Arch archive daily without interrupting development.

First you log in to vault and create a mirror:

vault:~$ tla register-archive foo@example.com--stuff-2004-SOURCE sftp://arch-server.example.com/home/arch/stuff/2004
vault:~$ tla make-archive --mirror-from foo@example.com--stuff-2004-SOURCE /backups/stuff-2004

You can then synchronise the mirror on vault with

vault:~$ tla archive-mirror foo@example.com--stuff-2004 

wait for this to complete, and backup the /backups/stuff-2004 using whatever mechanism you wish.

Should you ever need to restore from the backup, you need merely tar up the /backups/stuff-2004 directory (or retrieve same from your tapes), transfer it back to arch-server and remove the file called 'mirror' that you will find in its =meta-info directory. The last step is necessary to allow developers to commit to it again, since committing to mirrors is normally forbidden.