StorageTek Host Software Component 6 User Manual

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426   VM/HSC 6.0 System Programmer’s Guide
1st ed., 6/30/04 - 312579601
DETACHed from a virtual machine. This enables the volume to be available (that is, 
unselected) earlier than would otherwise be possible.
ACSPROP EXEC can also be used with VMOPERATOR to trap MOUNT messages for 
VMTAPE. LOGTABLE SAMPLE contains sample VMOPERATOR LOGTABLE 
statements to assist you. Consult VMOPERATOR documentation for information about 
tailoring the samples to your needs. 
Syntax 
Parameters 
There are no external parameters required. The PROP interface to an EXEC action routine 
provides parameters in the program stack. These are documented in the VM description of 
PROP. 
Usage Requirements 
The only requirement is that the PROP ‘logical operator’ have a link to the MAINTSTK 
RUN-disk.
Reduce Scheduling Contention 
Effective scheduling can increase library performance. Controlling the following 
scheduling related areas can help significantly in further increasing library performance:
• strive for a balanced workload 
• schedule nonproductive library activities during low-demand times. 
Balancing the Workload
If you experience higher than expected average mount times, but at the same time 
experience an improvement in production through-put, it could be an indication that 
your system is periodically flooded with work rather than having a balanced 
workload.
For example, all of your production jobs may be getting submitted at the beginning 
of a shift so that the library robots are overworked for the first few hours of the shift. 
Then, the robots may remain idle for the remainder of the shift. If you are using a 
scheduling software package and it releases jobs every hour on the hour, there may 
be tremendous tape transport contention for the first few minutes of each hour while 
the transports are unused for the remainder of each hour.
These situations tend to elevate average mount times; however, as long as the work is 
performed on time, there is probably no need to change conditions. However, if the 
work is not getting performed on schedule, you can improve performance by 
balancing your production workload. 
EXEC
ACSPROP