|Disk Library, Disk Library for mainframe, Virtuent|
How can I allocate scratch tapes more equitably across all eligible file systems?
How can I reduce an imbalance of scratch tape allocations?
Scratch tapes being allocated to a small subset of eligible file systems.
|DLm Release 4.5.0P1 has a bug that caused the DLm0047E and also caused the DLm0503E and the DLm0515W continuous messages.|
|There is a parameter setting that helps control where scratch tapes are allocated. This parameter is PENALTYUP. The following describes how to use PENALTYUP to resolve an imbalance of scratch allocations:|
The following guidelines should be used:
One shortcoming of PENALTYUP is that it applies to all tapelibs. For which tapelib should it be optimized?
To see the current penalty settings, the following undocumented command can be used: query tapelibs. This command displays data on every VOLSER range for every tapelib. For this discussion, the significant information it provides is each filesystemâ„¢s current penalty value & when it was last picked. Remember, the penalty starts at zero when the application starts, and goes up and down as scratch tapes are provided.
It might be good to experiment with the settings. Issue the set PENALTYUP command on all VTEs, and let it run for some time, issuing query tapelib from time to time to see the current penalty and when it was selected. Issue query space to see that status. If it is not selecting a number of ranges with free space around the recover amount (with available scratch space to be recovered) then PENALTYUP may not be high enough. But note that it will take some time (figure up to 100 mounts on each VTE in the tapelib in question) to adjust for previous settings; check the distribution after it has run a while after that adjustment.
Once a good value is selected, leave that setting and also update it in the xmap files.
|Notes||For a more comprehensive discussion of this parameter, including all the information above,see the "Understanding DLm Penaltyup" explanation on the EMC customer forums.|