Parallel Writes to Tape

Amanda can write to multiple volumes in parallel, saving a lot of time.

• A different dle is sent to each volume.
• All parts of a DLE are contiguous on a volume, although a DLE on several volumes may not begin at filenum 1 on subsequent volumes.
• If splitting is enabled and a volume becomes full, the next part of the dle can be on any volume, not necessarily on a new volume.
• The use of holding disk is still recommended, as it allows more dumps in parallel and many DLEs are not fast enough to stream a tape drive.
• If a drive is not available at the beginning of the run, amanda will not use it -- it doesn't poll for available drive.

Advantages

• Writing to many volume in parallel save times.
• Can do more than one dump direct to tape in parallel.

Disadvantages

• Requires a more powerful server to be able to stream multiple drives.
• Performance can be worse if the server can't stream all the drives.

Requirements

• A Changer with the new changer API must be used.
• More than one drive must be defined.

Global Configuration

The taper-parallel-write config option must be set to the number of volume amanda can write to in parallel. There is no other configuration for the feature.