All other things being equal, how would a storage array's IOPS performance change if one used larger disks.
For example, take an array with 10 X 100GB disks.
Measure IOPS for sequential 256kb block writes (or any IOPS metric)
Let's assume the resulting measured IOPS is 1000 IOPS.
Change the array for one with 10 X 200GB disks. Format with same RAID configuration, same block size, etc.
Would one expect the IOPS to remain the same, increase, or decrease?
Would the change be roughly linear? i.e. increase by 2X or decrease by 2X (as I've increased the disk capacity by 2X)
Repeat these questions with 10 X 50GB disks.
Edit: More Context
This question resulted as a conversation among my Sysadmin team that is not well versed in all things storage. (Comfortable with many aspects of storage, but not the details of managing a SAN or whatever). We are receiving a big pile of new Netapp trays that have higher disk capacity per-disk — double capacity — than our existing trays. The comment came up that the IOPS of the new trays would be lower just because the disks were larger. Then a car analogy came up to explain this. Neither comment sat well with me so I wanted to run it out to The Team, i.e. Stack-Exchange-land.
The car analogy was something about two cars, with different acceleration, the same top speed, and running a quarter mile. Then change the distance to a half mile. Actually, I can't remember the exact analogy, but since I found another one on the interwebz that was similar I figured it was probably a common IOPS analogy.
In some ways, the actual answer to the question doesn't matter that much to me, as we are not using this information to evaluate a purchase. But we do need to evaluate the best way to attach the trays to an existing head, and best way to carve out aggregates and volumes.
Best Answer
To answer your question directly - all other things being equal = no change whatsoever when GB changes.
You don't measure IOPS with GB. You use the seek time and the latency.
I could re-write it all here but these examples below do all that already and I would simply be repeating it:
https://ryanfrantz.com/posts/calculating-disk-iops.html
http://www.big-data-storage.co.uk/how-to-calculate-iops/
http://www.wmarow.com/strcalc/
http://www.thecloudcalculator.com/calculators/disk-raid-and-iops.html