How To:Write to Multiple Volumes in Parallel
Amanda supports parallel writes to tape, meaning that the Amanda server can send multiple DLEs to different volumes at the same time. This is useful if you write to more than one volume in a run and the changer have more than one drive.
Requirements
- A changer with the new changer API must be used.
- The changer must provide more than one drive
How to defined multiple drives:
- chg-disk: Nothing to do, an infinite number of drive is already available.
- chg-multi: Nothing to do, all drives are already defined.
- chg-ndmp: Define all drives with the tape-device property.
- chg-robot: Define all drives with the tape-device property.
- chg-single: Impossible to do, only one drive is available.
Configuration
Only one amanda.conf(5) parameter affects parallel writes:
taper-parallel-write 2
the number gives the maximum number of parallel writes that are allowed.
Examples
- chg-disk
taper-parallel-write 2 tpchanger "chg-disk:/path/to/vtapes"
- chg-robot
taper-parallel-write 2 define changer hp-robot { tapedev "chg-robot:/dev/sg1" property "tape-device" "0=tape:/dev/nst0" property append "tape-device" "1=tape:/dev/nst1" } tpchanger "hp-robot"
Note that, for the chg-robot configuration, the taper-parallel-write parameter must be less than or equal to the number of drives configured with the TAPE-DEVICE property.