Filter
Top Products
Characteristics. Flags for the PVR:
• Defer Dismounts. If ON, the PVL will delay the dismounting of a tape cartridge until the
drive is required by another job or until the Dismount Delay time limit is exceeded.
• Support Shelf Tape. If ON, the PVR and the PVL will support the removal of cartridges
from the tape library using the shelf_tape utility.
5.1.1.2.1. 3494 PVR Information Window
Field Descriptions
Server Name. The descriptive name of the PVR.
Total Cartridges. The number of cartridges currently being managed by the PVR.
Cartridge Capacity. The total number of cartridge slots in the library dedicated to this HPSS PVR.
This may or may not be the total cartridge capacity of the library; a site might use part of the library for
some other HPSS PVR or for some non-HPSS application. The PVR uses the Cartridge Capacity field
and the Cartridge Alarm Threshold field to determine when to send an alarm that the total cartridge
threshold has been exceeded.
Cartridge Alarm Threshold. The percentage of the Cartridge Capacity at which the PVR will send an
alarm.
Same Job on Controller, Other Job on Controller, & Distance To Drive. These values are used by the
PVR when selecting a drive for a tape mount operation. The three values are essentially weights that are
used to compute an overall score for each possible drive. After the score has been calculated, the drive
with the lowest score is selected for the mount. If two or more drives tie for the lowest score, one drive is
selected at random. The score is calculated as follows:
Score =
Weight 1 * Cartridges from this job mounted on this drive’s controller +
Weight 2 * Cartridges from other jobs mounted on this drive’s controller +
Weight 3 * Units of distance from the cartridge to the drive
This method has the effect of distributing a striped tape mount across as many controllers as possible for
the best performance. It also will try to pick controllers that are currently driving a minimum number of
tapes. So, in an environment with many tape drives per controller, the above algorithm will minimize the
load on any one controller.
The Distance To Drive helps minimize mount times by mounting the tape in a physically close drive.
For IBM robots, the time it takes to move a cartridge to a more distant drive is not significant, so the
default value here is fairly low. The unit of distance for a 3494 library is one frame. All other things
being equal, the tape will be mounted in the closest drive. However, if the closest drive is attached to a
HPSS Management Guide November 2009
Release 7.3 (Revision 1.0) 136