Re: System slow-down - disk usage?

On 16/06/2010, at 3:01 AM, Kurt Anderson wrote:

I also noticed that when the program is running with a large Previous file, that the page/fault ratio closes in on 3:1. Is this because the SetLL is moving through so much data? (No other batch jobs were running, and we have very little interactive use.)

Given the information provided so far it is probably that the input data is not sequenced by key and therefore the "compare to previous" operation is jumping all around the previous file thus causing excessive paging (at least of the index data).

I'm presuming processing like:
FINPUT IF E DISK
FPREVIOUSIF E K DISK

.... start loop
C READ INPUT
C KEYL SETLL PREVIOUS 55
C *IN55 IFEQ *OFF
C ... do stuff
C ENDIF
.... end loop

**RPG/400 just for irritation value :)

Perhaps sorting the input data into key sequence prior to processing will help? Doing so will keep the SETLL requests within current data. Paging will still occur but you won't be faulting on data previously loaded and purged. Sorting the input will also you to use double- buffering with a large block size.

It's also possible that the volume of input data is such that it causes pages from the previous file to be constantly purged in which case using SETOBJACC to bring it into a separate dedicated pool may help.

Regards,
Simon Coulter.
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