Storage Area Network (SAN)

A Storage Area Network (SAN) is very similar to a data network, except that it is used to connect storage devices (such as disk arrays, tape libraries, etc.) to servers (host computers) in a remote fashion, instead of using a “direct attached” storage model.  Direct Attached Storage (DAS) is when the system disk is physically housed in the same enclosure or box as the main computer, or is relatively close by.  SANs use the same communications model as DAS, but the storage devices are normally connected to a separate network of storage devices that physically separate from the servers.

In today’s world, the majority of SANs are built using a Fibre Channel (FC) infrastructure, because of the speed and reliability characteristics of FC.  But that may be changing soon.  With the increase in speed that is occurring in the Ethernet and IP world, data storage traffic can move across Ethernet-based networks with the same characteristics of a native Fiber Channel network.  This is a “good thing” because a major cost (disadvantage) of building a SAN has been the components, such as Fibre Channel switches and Host Bus Adapters (HBAs).

Development is currently in process for what are called “Converged Network Adapters” (CNAs), which are capable of carrying multiple types of data traffic, including storage traffic, in a “reliable” way and with newly developed or enhanced protocols that can deal with Quality of Service (QoS) and error handling, without the large overhead of typical networks that use TCP to deal with the connections and recovery of lost data.

These new developments pave the way for a less expensive infrastructure, and protocols like Fibre Channel over Ethernet (FCoE) and iSCSI to become alternate choices for building a SAN.

So what will be the best storage area network to build or use in your company or system?  The answer is: It depends!  Factors such as speed, reliability, applications that need to be supported, and budget, all come into play.  Are you going to build and maintain the SAN yourself (DIY SAN), or are you going to look for a SAN solution provider to provide this type of service for you?  If you are new to the SAN world, my best recommendation would be to do your research and look for a provider that has a good track record of support and service.

The best storage area network is the one that does what you need it to do, in a reliable, repeatable way.  If a SAN solution provider can make that happen for you in a cost effective way, give them a shot.

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