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The Question is:
We have a Alpha 1200 5/533, Model 1736. Is there a document that will help me
interpret the VMS Monitor Utility statistics as they relate to this Alpha.
Example: If TOTAL DISK I/O is 67/second is this OK on Alpha. What is the
maximum DISK I/O Alpha 1200 will support?
Thanks,
Pat
The Answer is :
The OpenVMS Wizard is not aware of information available to the level
of detail that you seek, as the permutations -- disks and disk spindle
performance, SCSI controllers, SCSI configuration specifics, contention
from other hosts on the same SCSI, caching and application I/O patterns,
etc -- are huge.
Key among disk access specifics here are the disk queue lengths, and not
the disk queue rates -- disk queue rates above 0.5 indicate that at least
half of all I/O is waiting. If the queue lengths climb, the aggregate
I/O rate is too high.
Also of interest would be I/O caching efficiency, as a correctly tuned
application will often tend to be CPU-bound, and not I/O bound -- CPU
and memory (cache) are far faster than physical disk media. (OpenVMS
V7.3 and later has XFC support, a wholely new I/O cache design.)
For general performance information, please see the performance manual.
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