The proliferation of huge, cache-laden SATA disks in the consumer market has led to an ever-expanding array of very inexpensive networked storage products for business. More often than not, these devices offer both NAS and iSCSI SAN functions that, until recently, were found only in enterprise-class storage products -- at a fraction of the cost. Are these ultracheap alternatives right for you? That depends on who you are and what you do.
A huge range of performance variables separate true enterprise-class storage products from their inexpensive pretenders. The most glaring is transactional performance. Most low-cost storage devices are based on a small number of very large SATA disks rather than larger numbers of SATA or higher-speed SAS/FC disks. These types of configurations will yield extremely anemic transactional performance, which would generally make them poor choices for hosting a busy database or mail server.
What if that's not what you want, though? If you're a small business without a whole lot of transactional disk performance needs or a big business that just needs a very large, low-cost parking lot for some big data, are these low-end storage devices a good option?
That question is more difficult to answer than it seems. The answer depends less on the actual technology at play and more on who is going to be supporting and depending upon it.
What "Enterprise Class" Really Means
First off, let's take a look at what most people mean when they talk about an "enterprise class" storage array. Higher price is certainly part of it. But to my mind, the real definition has everything to do with how the original manufacturer designed the product to be used -- keeping in mind that this is not always synonymous with how it is being marketed (a lesson that can be expensive to learn the hard way).
An easy test is to imagine yourself using the product for whatever you want to use it for -- maybe running a virtualization cluster for a small business -- and then having the device utterly fail. Are you relying on the storage vendor to resolve the situation for you, or do you have your own recovery plan to throw into action? When you call the storage vendor to get support, what will the reaction be? How deeply will your users be impacted? Can they still do their jobs?
Chances are, if you're running an enterprise-class storage product, the "failure" of the product wouldn't be a failure at all. It would be an amber light on a controller, power supply, fan tray, or disk and a warning telling you that you should probably get it replaced. You call the vendor (assuming you bought support) and they ship you a new one. You slide the replacement component into the device and off you go. Production hasn't been impacted and you're back where you started.
On the Low End, Be Prepared
If you're running a low-end device, you might not have a support number to call. Even if you do, don't plan on getting a replacement component the same day or even the same week. Worse still, don't imagine that the component you get is going to simply fix the problem all on its own. In many cases, a hardware failure in a low-end NAS/SAN device will necessitate a full restore of the data that was on the device onto a completely new device. Most of the devices in this space are not designed to be modular beyond having RAID and replaceable disks. If you have a controller failure, you're probably starting over with a backup.