SQL Server 2014, Volumes in Resource Governor

Question

I'm looking at Resource Governor on 2014 and how it relates to volumes. I can see where to set up MAX|MIN IOPS PER VOLUME on a resource pool. That's not keyed by volume, however sys.dm_resource_governor_resource_pool_volumes is. Should I read that as the pool's definition applies to every volume but the DMV reports what actually happened on each?

My understanding is this: say I have three volumes - E, F and G. I set min = 10, max = 300 on the pool. Then there can be, at most, 300 IOPS against each drive for a max of 900 for the pool. The DMV shows what IO actually happened for each volume. If the table/filegroup definition were such that the majority of the activity happened on one volume (let's say F) the numbers from the DMV would show large read_bytes_total and write_bytes_total for that volume and smaller numbers for the others. Is this a correct understanding?

Neither BoL nor any of the blogs I've read make this explicit.

Answer 1

It seems reasonable to assume, per the documentation and indeed the names of the parameters themselves, that MIN_IOPS_PER_VOLUME and MAX_IOPS_PER_VOLUME control the maximum quantity of I/Os per second per volume.

i.e. as in your question, if you have three volumes in the resource pool, and set MAX_IOPS_PER_VOLUME to 300, then you'd have a maximum total IOPS of 900.

Without source-code-level access to SQL Server, it's impossible to say for certain if that's how it actually works, however the documentation says (emphasis mine):

MINIMUM_IOPS_PER_SECOND:
Specifies the minimum I/O operations per second (IOPS) per disk volume to allow for the resource pool.

MAXIMUM_IOPS_PER_SECOND:
Specifies the maximum I/O operations per second (IOPS) per disk volume to allow for the resource pool.