VAAI, More Than Just a Firmware Update
Now that VMworld is over, I can start the very long process of digesting all of the information from the show. One of the most important things I have been investigating is the vStorage APIs for Array Integration or VAAI (see
my earlier post on VAAI). With vSphere 4.1, administrators can send a tremendous amount of work usually handled by the ESXi host to the storage processor.
At face value, it makes quite a lot of sense for this type of work to be done on the storage processor and may seem like an incremental software update. The hidden story here is that there is quite a lot of work that goes on behind the scenes to get this solution out the door.
The first release of VAAI includes three tasks that make use of an unused SCSI reserve command. Early adopters have been discussing what the first three commands would be, as well as what the next three commands will be to offload work from the ESX host. For example, NetApp's Rapid Cloning Utility (RCU) effectively did this for one task ahead of the VAAI movement. While first iteration has support for atomic test and set, clone blocks/full copy/xcopy and zero blocks/write same; there is quite the complicated affair to identify the next steps for VAAI. Each storage company will bring different ideas, capabilities and turnaround to the next line of features.
There is a very small list of storage companies in the initial wave of support: Dell's EqualLogic, 3PAR, NetApp, Hitachi Data Systems (HDS) and EMC. But even within that list, not every product is ready to go with a firmware update or shipping product at the release of vSphere 4.1. Some storage products do not support it currently, but will with upcoming firmware updates. A few products are available from day one, such as the HDS Adaptable Modular Storage 2000 (AMS 2000). In the case of the AMS 2000, existing installations had to implement a new firmware revision and new shipments after the release of vSphere 4.1 had support for VAAI.
VAAI brings amazing performance improvements for the virtualized environment. Dare I go out on a limb and make a recommendation that new purchases include arrays that support VAAI? The vSphere 4.1 upgrade is the (relatively) easy part; but getting a VAAI-supported array may be the harder part due to product lifecycles and maintenance windows on the storage processors.
We all can agree that VAAI is cool, but are there stumbling blocks to get there? Share your comments below.
Posted by Rick Vanover on 09/09/2010 at 12:48 PM