What you need to know about SMB SANs

SMB storage area networks (SANs) have come a long way in the past few years, offering functionality and performance typically associated with enterprise-class products. In this Q&A with Marc Staimer of Dragon Slayer Consulting, learn who needs a SAN, how to choose the correct protocol for your needs, the advantages and disadvantages of multiprotocol storage, and important recent developments in SMB SAN technology. You can read the Q&A below or download a recording of the conversation.

Listen to the SMB SAN FAQ.

How do you know if you need a SAN?

The key word there is "need." Need is an interesting question because a lot of people think that they need something they don't. A lot of it comes down to what they read in the trades, or what they are told by a vendor, or just what they think they need. What it comes down to is the type of data that you are storing.

For example, if you have a lot of structured data—database data, this type of data requires low latency. Database data requires high-performance storage. In a lot of cases that means SAN storage.

SAN storage means that the ports on the storage device can be shared via a switch so you can have more than one physical server accessing each of the ports. You can think of it as an early form of virtualization. You are virtualizing access to each port. Before SANs it was a one to one relationship—one server to one port.

So if you need shared storage, low latency, and high performance that may be an indicator that you need a SAN. What has changed however is that a lot of network-attached storage (NAS) has improved performance and improved latency, so in many cases you don't [need a SAN].

One other thing to consider is that you need SAN or NAS shared storage for virtualized servers.

ISCSI or Fibre Channel? Which is more suitable for an SMB SAN?

Actually, you have six different SAN choices, not just two. iSCSI and Fibre Channel are the ones most people think of when you think of a SAN. But, there are four others.

You've got InfiniBand, which has been around for awhile and is geared toward high-performance, clustered environments. That can be a good choice for a SAN. You've got Fibre Channel over Ethernet (FCoE), which is part of Converged Enhanced Ethernet (CEE). There are two others that are less well known but are becoming relatively popular among SMBs. The first is ATA over Ethernet (AoE). That is currently only available from one vendor, Coraid, but it is an open standard. And the other is serial-attached SCSI (SAS). SAS SANs and AoE SANs can be very inexpensive and work well for SMBs.

Which one do you pick? It comes down to what your knowledge base is, what your skill set is, what your infrastructure looks like, and your budget. The most expensive is FCoE, followed by Fibre Channel, InfiniBand, iSCSI, AoE, and SAS. If you have a larger environment, you really can't use SAS.

What does multiprotocol storage mean, and what are the advantages of a multiprotocol system?

Well, it depends on the vendor. There are different storage protocols. You have the Fibre Channel protocol, which is SCSI in a Fibre Channel frame. You have iSCSI, which is SCSI mapped to TCP/IP. You have the network-attached storage protocols NFS, or network file system, which is a standardized protocol for unstructured data. You have CIFS, computer internet file system, which is also for unstructured data. You have HTTP which is part of the REST interface. Then there is ATA over Ethernet and Fibre Channel over Ethernet. And then there's SAS.

When a vendor says they are multiprotocol you have to first find out which protocols they mean and whether or not they are suitable for you. The advantage is that it gives you choices and options. The disadvantage is that this type of system can be a jack-of-all-trades but master of none. Usually a system that provides everything isn’t going to be perfect for anything.

What do you think is the most important recent technological development in the SMB SAN space?

That is a very difficult question. You'd have to say it's primarily on the SAN storage side not necessarily on the network side. Simplicity of management is a key factor. Anything that puts the expertise into the storage system vs. the network or the administrator, that's a good thing.

Another good one is the advent of virtualized SANs, which provide the SAN capability in a virtual server environment. So you don't have a physical SAN it just runs on Ethernet pretending to be an iSCSI SAN and works reasonably well for small environments. Virtual IO based on multi-route IO virtualization or even single-route IO virtualization—that allows IO to be virtualized with physical servers or virtual servers. That gives you much better utilization of your bandwidth. Those are all areas of immense improvement for the SMB SAN.