I took the opportunity last week (while I was over in the Boston area) to catch up with Scott Davis. I’ve known Scott a long time, as he had various roles at VMware over a number of years. Scott is currently CTO at Infinio, a company that has developed an I/O acceleration product for virtual machines. The new version of Infinio Accelerator 2.0 released only a few weeks back, so I decided to reach out to Scott and find out about the enhancements that went into this new version.
My colleague Duncan wrote a post relatively recently around the new mclock I/O scheduler which VMware introduced in vSphere 5.5. He also mentioned some caveats with the new scheduler, especially around the I/O size (32K) used with the IOPS setting, which may lead to some unexpected behaviour. As Duncan mentioned, the reason for introducing the new scheduler is primarily to provide a better I/O scheduling mechanism that allows for limits, shares and reservations. Unfortunately, we didn’t do a very good job of announcing this change in I/O scheduling, or documenting the behaviour, and it has led to a number of…