How To:Write to Multiple Volumes in Parallel

From wiki.zmanda.com
Revision as of 20:14, 28 September 2010 by Martineau (talk | contribs)
Jump to navigation Jump to search

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

This is useful if you write to more than one volume in a run and the changer have more than one drive.

  • A different dle is sent to each volumes.
  • All parts of a dle are contiguous on a volume.
  • If splitting is enabled and a volume get EOT, 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, it allow 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.

Advantage

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

Disadvantage

  • Require 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.

In amanda.conf: 

taper-parallel-write 2

Changer Configuration

How to defined multiple drives:

  • chg-disk: No configuration needed. An infinite number of drive can be use.
  • chg-multi: All drives already defined, nothing to do.
  • chg-ndmp: With the tape-device property.
  • chg-robot: With the tape-device property.
  • chg-single: Impossible to do, only one drive is available.
Retrieved from ‘http://wiki.zmanda.com/index.php?title=How_To:Write_to_Multiple_Volumes_in_Parallel&oldid=7715’