Re: New SSD options for IBM Power Systems provide enhanced performanceat a lower cost

DrFranken <midrange@xxxxxxxxxxxx>
wrote on Wed, 20 Apr 2016 02:59:11 GMT:

Performance tools will do a much better job but this will give
you that general idea starting point and it may surprise you!
ALSO Note that this may swing wildly depending on workload at
the moment!! You need to consider the entire day.

You absolutely have to use collection services data if you will
consider moving to the new RI SSD because

- CS data is the only place where you can see actual writes to
the devices not just system level writes (WRKDSKSTS only shows
system activity).

- CS data is the only place where you can see write cache
effectiveness. This means data didn't go to the device (HDD or
SSD), it was updated in cache before it needed to be written.

Both of these factors WILL CHANGE when you change your device
count and when you change IOAs, but if you don't know where you
are, you can't even begin to predict where you might be.