Behind NSX, VSAN was the next most talked about item at VMworld US 2013 and for a good reason. VSAN introduces the opportunity to change the way storage is used in the datacenter. VSAN also introduces a paradigm shift for VMware. Prior to VSAN, VMware encouraged the use of shared storage to leverage features like DRS and HA. The importance of locally attached disks was minimized even more with the support of boot from SAN and auto deploy. Now with VSAN and vFlash, local disks are important again, but is the change coming too late?
With any paradigm shift change comes slowly. Virtualization did not explode overnight and neither did trust for features like DRS and HA. Slowly technology is adopted and slowly infrastructure changes are applied. Even once the decision is made to change directions it is usually not an all or nothing approach. I mention this because I have heard several people comment that the VSAN technology is coming too late. That too many people rely on share storage and have done away with local disks. I would like to address these claims.
I would agree that many people leverage shared storage to get features like DRS and HA. I would also agree that in general local storage is not a priority when purchasing a virtual environment. I do not agree that datacenters have become shared storage only. I would also state that many people are not happy about their shared storage complexity and performance. At the end of the day, it comes down to requirements. For a SMB shop, a shared storage device usually means a dedicated storage team as storage may be cheap, but it is not easy to operate. It also usually means another silo in the organization. What companies and especially SMBs are looking for is simplicity.
In addition to simplicity, companies care about availability and performance. In regards to availability, wouldn’t it be nice to say I want this VM to have availability X while this VM to have availability Y? And wouldn’t it be nice to change availability without having to reconfigure your storage? As for performance, what better way to get performance then from a source dedicated to a subset of an environment? If fast storage can be provided closer to the VMs that are running on it and if fast storage can be replicated to fast storage then performance becomes easier to measure and guarantee. Centrally sharing things like storage provides opportunities for new features, but also opportunities for new failures and limitations. By locally centralizing you get pools of resources. In addition, with VSAN you can scale-out and of course software-defined storage.
In short, VSAN opens the door for more innovation and more ways to better manage an environment. In my opinion, it is a great option for SMBs looking for a cheaper and easier way to leverage features that require shared storage.
© 2013, Steve Flanders. All rights reserved.