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The Question is:
What on a VAX system should be modified to increase the speed of truncation of
data files that are created with large allocated size at process start? Is
this a disk MOUNT, set file cache size problem? or an ACP_<cache> issue? or both?
Thank you for your help!
The Answer is :
Most obviously, the speed of the VAX processor and the performance of
and the typical load on the I/O subsystem would all be of interest
when seeking to improve I/O performance. (OpenVMS Alpha systems have
far faster processors and far faster I/O subsystems.) Process quotas
can also enter into the discussion, particularly if overly constrained.
Depending on the access pattern, storage attributes such as highwater
marking or erase-on-delete can also have an effect on performance.
The default file extent size value can be set on a system-wide, process,
volume, or application basis. Via SYSGEN SHOW/RMS, via SET/SHOW RMS,
via SET/SHOW DEVICE, or via RMS or XQP service APIs, respectively.
The OpenVMS Performance Management Manual will be of interest, as a
start.
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