We want to add a disk offering where we can specify the Min/Max IOPS as a function of size. The idea is the larger volume you create, the greater your IOPS will be (this is similar to the way GCE handles IOPS). We also have added limits to the IOPS (min and max) so that once the volume goes beyond a certain size, the IOPS won't change and are capped to the given values.
The following parameters are added to the `createDiskOffering` API:
1. `miniopspergb' : Minimum IOPS/GB for the offering
2. `maxiopspergb`: Maximum IOPS/GB for the offering
3. `highestminiops`: The highest `miniops` value that is allowed for this offering
3. `highestmaxiops`: The highest `maxiops` value that is allowed for this offering