[Info-vax] RX2800 sporadic disk I/O slowdowns

[Richard Jordan]

Followup on this.  I'm looking at one of Hein's presentations on RMS 
indexed files, tuning, etc.

Presuming the system has plenty of memory and per autogen its state of 
tune is pretty close to what autogen wants, is there any downside to 
setting a count of global buffers on the large indexed data files 
involved in this issue (the ones that show extended 'busy' channels in 
system analyzer)?  Can it cause any problems that would impact production?

We already tested setting a modest process RMS buffer count for indexed 
files on the accounts used for batch operations, and that seems to make 
a modest improvement in runtime and a significant reduction in direct 
I/Os.  Saved 3-4 minutes on a 32-34 minute runtime but DIOs dropped from 
~5.1 million to ~4.3 million.

Unfortunately we still had two jobs run long, one over 7 hours so they 
killed it, the other about 4.5 hours but with the same reduced 4.3M DIO 
count.  So it helped in general but did not make a difference to the 
problem.  I don't expect the global buffers to fix the problem either 
but its worth testing for performance reasons.

Thanks