Networked storage scares many IT folks at growing businesses. Servers come with their own hard-disk storage, or direct attached storage, just like notebooks and desktops. When there are one or two servers, it’s easy for users to share files on the internal storage of one server and run applications such as e-mail hosting on the other, which lets IT workers stay within their comfort zone.
But the tidal wave of server virtualization can easily push technicians out of that zone of comfort. Server virtualization — whether used to reduce the number of physical servers, add redundancy or provide a way to test applications — means no more depending on direct attached storage.
Well, technically, that’s not true. Businesses can virtualize a server and boot and run virtual machines from the hard disk or disks inside that one physical server. Server performance will be fine, because there is plenty of throughput across a motherboard to a disk interface for almost all applications. Some companies even add a disk or two inside their physical servers to store various virtual machine instances to reduce the damage if their primary hard disk fails. That also avoids moving to networked storage.
Honestly, that approach is a delaying tactic and a mistake. Companies might as well ramp up the learning curve for server virtualization and networked storage at the same time.
The mirror-image acronyms of NAS and SAN refer to completely different ways of using storage. NAS (networked-attached storage) appliances are specialized computers that include one or more hard disks. They connect to your network, not to your server.
NAS appliances are inexpensive (one-disk units that cost about $150 are available but won’t work with virtual servers) and easy to manage, and are a typical first step into networked storage. Workgroup-level appliances — from vendors such as Buffalo Technology, Cisco Systems, Iomega, LaCie, Netgear and Seagate Technology — offer extra storage for companies when their server storage is getting low. Multiple drives provide redundancy, and fast network connections support clients that need private and shared folder space. You may have a couple of these already.
Fortunately, most of these units also support virtualized servers. Totally separate from your physical server, the NAS appliance holds the virtual machine boot and data files needed to run a virtual server. Because these workgroup NAS appliances cost around $1,000, plus or minus a couple hundred, these are great ways to jump into network storage to support virtualization.
The big brother of workgroup NAS appliances are enterprise NAS systems. Typically, the difference is rack mounting and the number of drives supported, which also means more capacity. All enterprise NAS systems, often called NAS storage servers, work quite well with virtualized servers. Many companies mount server and storage appliances in the same rack.
Make the move to SAN systems when more capacity, reliability and performance are needed. Unlike NAS servers, which follow a folder storage format, SAN systems use block-level storage to the disk. Thus, a SAN needs a server in front of the storage appliance to manage reading and writing data to disk blocks and to manage multiple users accessing those blocks. That means more equipment, more complexity and more expense. But if you look to your virtualized servers to provide failover and high availability, they need a SAN to provide performance and redundancy.
The good news is that NAS appliances can cost less than desktop computers, and SAN systems can cost less than servers. They can cost a lot more, too, but by the time you need that type of SAN, you’ll be way down the virtualized server road and up into private clouds. Enjoy the view.