This is Part 2 of my previous blog about VAAI (vStorage API for Array Integration) with more details about VAAI. VAAI offloads some of the I/O related functions to the VAAI-enable storage array, hence giving the hypervisor more compute and memory resource to do it other functions. And the storage array, upon receiving the VAAI command, will execute whatever that is required of it.
Why is VAAI important? What does it do that makes it so useful and important to the hypervisor?
VAAI is about a set of new SCSI commands. And there are 3 important ones:
And if you want to see the VAAI Hardware Accelerated Full Copy (aka XSET) in action, here’s a little video showing how it is done in an EMC environment.
The primary significance and noticeable benefit is definitely performance. The secondary benefit, though not so obvious, is allowing VMware and its hypervisor to scale because it does not get bogged down by some of the I/O functions that it is not meant to do.
There were some new additions in vSphere 5.0 for VAAI. From its FAQ, it listed in ESX5.0, support for NAS Hardware Acceleration is included with support for the following primitives:
- Full File Clone – Like the Full Copy VAAI primitive provided for block arrays, this Full File Clone primitive enables virtual disks to be cloned by the NAS device.
- Native Snapshot Support – Allows creation of virtual machine snapshots to be offloaded the array.
- Extended Statistics – Enables visibility to space usage on NAS datastores and is useful for Thin Provisioning.
- Reserve Space – Enables creation of thick virtual disk files on NAS.
So, there you have it folks. Why VAAI? Here’s why.
Posted on January 6, 2012, in Virtualization, VMware and tagged Hardware accelerated full copy, Hardware accelerated full zero, Hardware assisted locking, hypervisor, LUN, performance, SCSI, VAAI, VMware. Bookmark the permalink. 3 Comments.