The time has come to retire the NAS/SAN false dichotomy.
If you have spent any amount of time in the Storage industry, you have invariably observed that Network Attached Storage (NAS) is often projected as the opposite of a Storage Area Network (SAN). NAS is file and SAN is block, right? Well, just reading the acronyms out loud should give you your first clue that something is amiss: one is a category of storage while one is a category of network. Both terms entered popular usage in the early 1990s and over time have taken on subjective meanings for just about every storage user, administrator, and vendor you talk to. The resulting loose consensus is that NAS leans towards “file sharing services over Ethernet” and SAN towards “a Fibre Channel network dedicated to shared block storage”. I will not disagree with these tendencies, but will argue that they represent a false dichotomy that is doing a disservice to the storage industry for several key reasons:
- “NAS” systems are increasingly “unified”, supporting not only file and block services but now object storage protocols and version control software protocols.
- Ethernet has become a popular, often-dedicated transport for network-attached block storage, making a SAN synonymous with a commodity LAN in many cases.
- NAS has a clear antonym: Direct-Attached Storage (DAS).
- SAN lacks a clear antonym and it is certainly not “NAS”.
Any data storage accessed over a network can safely be called “network attached storage”, regardless of the actual network fabric. The SNIA Dictionary “specifically does not identify the term SAN with Fibre Channel technology” and suggests that references to Fibre Channel should be qualified as “Fibre Channel SAN.” I contend that accurate dichotomies are needed to do justice to specific technologies like Fibre Channel and the broader categories of block storage and dedicated storage networks. After all, there are standards for Fibre Channel over Ethernet and Internet Protocol over Fibre Channel.
Your accuracy with storage terminology will make you a better consumer and manager of storage technology. While enough research will generally untangle any confusion over NAS versus SAN, understanding the distinctions between snapshots, backups and archives can have a direct impact on the safety of your data, and even legal ramifications when it comes to data retention obligations. The Sales and Engineering Teams at iXsystems are here to help you navigate every aspect of storage terminology and determine the best storage solution to meet your needs.
Michael Dexter, Senior Analyst