Storage Protocol Selection

In IT there always seems to be an effort to consolidate something. We've consolidated servers with server virtualization, attempted to consolidate storage with SAN and NAS, attempted to consolidate the management of storage tiers with automated tiering, but what about protocols? They just seem to continue to proliferate. Which storage protocol should you select?There certainly are more than enough choices. We have SCSI, which grew into Fibre, out of that grew iSCSI in an effort to drive down the cost of storage. NAS (Network Attached Storage) has moved from just being a file sharing service to something that hosts databases and virtual machine images. FCoE (Fibre Channel over Ethernet) has come on the scene in an attempt to consolidate IP and fibre and now we have new protocols emerging like ATA over Ethernet. Also factor in that most drives are going to SAS (Serial Attached SCSI). It enough to drive a storage manager crazy.

There does seem to be one common ground in all the protocols. Ethernet seems to eventually win out. While the transition from traditional fibre can be as slow and steady as you choose, eventually it seems that everyone will be running on some form of ethernet. That however does not really consolidate the protocol choices, just the cables they run on and the cards they use.

There also are more than a few companies providing unified platforms; essentially storage appliances that support many of the different protocols. While these systems fill a need, the storage manager still has the challenge of deciding which supported protocol to select and if for some reason they need more than one, management of multiple protocols can be a problem.

Its our belief that organizations step into shared storage sooner than ever thanks to server virtualization. For a single protocol to emerge or at least a dominant one, we are going to need to see something that meets the needs of the first time shared storage user and then scales to meet the needs of the very large data center. iSCSI could be ideal since it can start as simply as a software based initiator and run on the current network. Both of these factors keep costs down. Most first time users of shared storage do not need the sophistication nor high performance of the other protocols.

NAS can play a similar role here especially in virtualized environments. NAS's challenge is if there is a database or mail server in the organization that does not support having its data on a network mount point and if that application is not virtualized than you have to introduce a different protocol or use direct attached storage. As mentioned earlier an increasing number of NASs offer an additional protocol, typically iSCSI, but many now include fibre. Again you have introduced another management point. Its how these unified devices make it to manage multiple protocols that becomes critical.

As the organization grows either of these IP based protocols can grow with it. It is however fair to say that as they scale at some point iSCSI and/or NAS become as complex as fibre is perceived to be. You have to manage and understand separate networks, specialized or high speed cards, specialized frame sizes etc. A little research on the term iSCSI Optimization will reveal volumes of articles and blogs and when you digest them they start to sound very similar to fibre channel optimization.

In our next entry we will look at fibre and FCoE, can they take that step to eliminate the need for other protocols?

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George Crump is lead analyst of Storage Switzerland, an IT analyst firm focused on the storage and virtualization segments. Find Storage Switzerland's disclosure statement here.