Sysparms to improve performance

Document ID : KB000055748
Last Modified Date : 14/02/2018
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Setting the following sysparms may help improve performance of Backup, Archive and IXMAINT; (See System's Guide for additional information)

IOCHNBLK (1-9): Setting this sysparm to a value higher than the default of one will cause BrightStor CA-Disk Backup and Restore, during backup and archive, to chain multiple blocks of data (that would have each required their own I/O) together. The result is more data transferred per I/O and fewer I/O's overall so run-time decreases.

SMSCACHE (Y/N): Overriding this to Y will cause IXMAINT to table in memory any SMS construct acquired to process an SMS managed data set in the files data set to determine if the data set entry should be expired. If you have 200,000 SMS managed entries in the files data set, 200,000 accesses to SMS will be required to get the constructs or rules at the default setting. If the 200,000 entries break down into 30 unique constructs, with SMSCACHE active, only 30 accesses will be required.

IXMQTIME (nnnn): At a non-default setting, this sysparm causes IXMAINT to release and reacquire the files data set enqueue every nnnn tenths of a second. As a result, anything waiting to use the files data set will get access to it after waiting only nnnn tenths of a second. This sysparm essentially removes any need to worry about when IXMAINT should be run for fear of impacting other jobs that need access to the files data set.

IOTRACKS: Allow the default value to be used so that a complete cylinder will beread or written in a single IO.