Parallel Writes to Tape
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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.