What are the benefits and drawbacks of using a unified storage array in a virtual server environment?
Here's the way I use the term unified storage. It's really a combined SAN and NAS in the same array where a gateway controller at the front end directs where the appropriate location is for the I/O. In other words, it's a combined block and file system rather than a separate SAN and NAS. Usually it's in combination with a converged 10 GbE network.
The pros of going with a system that has an all-in-one storage architecture is that it's really a simpler deployment out of the box. You don't have to worry about how to deploy and scale SAN versus how to deploy and scale NAS. You're able to do it in one single device. And you have a single set of management utilities that will help you manage the unified storage array, set up resource pools in a virtual environment, and make it easier to manage virtual machine movement across the storage estate because it's all under one roof.
The difficulty is that, like most all-in-one types of appliances, not only do you get the best of both worlds, but, in some cases, you also get the worst of both worlds. And in this particular instance, it means a bunch of different workloads are running in the same storage environment and you have problems with things like the noisy neighbor issue. In addition, how do you appropriately allocate resources from one job to the next job, or one workload to the next workload?
If you have a high-performance requirement for a specific application, you'll probably be better off with a standalone SAN system where you can deliver that kind of performance. Conversely, if you have a very large -- millions or tens of millions of files -- you may be better off with a scale-out NAS system rather than trying to do both.
The bottom line here is if you have a mixed workload environment where you don't have any of those special performance or scaling requirements, a unified storage array system can be just the right deal.
This was first published in January 2014