Is NAS all about file sharing or what? Can you have direct connections from clients to servers or are connections only on the network? How does it differ with SAN?
NAS was primarily used for file sharing initially and it does that very well. Recently the usage of NAS has expanded for a variety of purposes (including backup now) all based upon capacity and performance improvements that have been made. NAS does file I/O while SAN does block I/O. Some applications may have certain requirements that make block I/O preferable. It all depends on your requirements for performance, security, etc. There isn't a simple answer and it is getting somewhat confused with varying "SAN/NAS convergence" solutions. This area is still in its early stages so there will be many new products and degrees of maturity.
NAS does connect over a local area network. Most are implemented using Ethernet of some speed but there are other technologies such as ATM supported by a few vendors.
Evaluator Group, Inc.
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This was first published in June 2002