Shmuel Metz (Seymour J.) wrote:
In <[email protected]>, on 03/24/2011
at 02:04 PM, Dave Roeser <[email protected]> said:
Anyway, he wishes to know if this is an "in-storage" sort or is it to
use external media?
What's the working set? If the data are larger than the working set
then he will see paging, and will need to analyze the tradeoffs
between paging I/O and explicit I/O to external media. He might need
to tweak his reference pattern to get good performance.
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In my experience, which is admittedly not infinite, I've learned that
allowing SORT a reasonable region size and using the SORTWKxx files hs a
less deleterious effect on overall system performance than simply giving
SORT a huge region and just letting it page.
Let us always remember that paging is bad. It is non-productive I/O and
cycles spent that produce no useful work, other than shuffling things
around and impacting everything in the system. At least DFSORT can
determine when it's necessary to do I/O to SORTWKxx files and schedule
it such that it has least impact on the task at hand, as well as other
tasks within the system.
Rick
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