Re: STRASPBAL on guested partitions

wrote on Fri, 24 Jul 2009 12:25:33 GMT:

3 - I am sure that a *CAPACITY will get them back in balance.
However, once balanced, shouldn't they stay on roughly the
same percentage? I have several other systems and WRKDSKSTS
doesn't show them 0.1% off. However on virtual disks they are
off double digit percentages.

I've seen this behavior too but was not able to take the time to
run it back to development to see what may be happening.
Although, I'm not too sure that it really makes a lot of
difference when dealing with virtual disks.

wrote on Fri, 24 Jul 2009 14:04:29 GMT:

So when you run STRASPBAL *USAGE on HOST how would
it know that file XYZ on GUEST is heavily used? It wouldn't.
What it may know is that
/QFPNWSSTG/GDISTG01
or
/QFPNWSSTG/GDISTG02
or both, is heavily used and scatter that around?

What gets moved when balancing based on usage varies depending on
whether you have solid state drives (SSDs) or not. Assuming no
solid state drives, understand that balancing based on usage does
not move "hot" data. It moves cold data to hot drives so new
data is less likely to go there using the premise that new data
is more likely to be accessed than old data. NWSSTG extents do
not get moved around when balancing.

This changes when SSDs are installed so hot data does get moved
to the SSDs and cold data is left on spinning disks. The target
is to get approximately 1/2 of the reads coming from SSDs versus
spinning disks.