How do I back up and restore the queue disk?
You can’t. One difficulty is that you can’t get a consistent snapshot of the queue while qmail-send is running. Another difficulty is that messages in the queue must have filenames that match their inode numbers. However, the big problem is that backups—even twice-daily backups— are far too unreliable for mail. If your disk dies, there will be very little overlap between the messages saved in the last backup and the messages that were lost. There are several ways to add real reliability to a mail server. Battery backups will keep your server alive, letting you park the disk to avoid a head crash, when the power goes out. Solid-state disks have their own battery backups. RAID boxes let you replace dead disks without losing any data. 7.7.
