I have come to believe that the core consideration for evaluating file servers and NAS is the file system technology. Functionally, this is where I see the greatest differences between the different OS and NAS vendors. If the application is to serve files, isn't a NAS device a file server and conversely, isn't a file server such as an NT box a NAS device? Is the definition of NAS based on advanced capabilities of the file system or the fact that the underlying operating system has been stripped of all processes unrelated to file serving? Do the network packets from a NAS device differ from those of a file server given the same network file system such as CIFS?
A NAS is a specialized file server sometimes implemented with custom hardware and custom operating system. There are other distinguishing elements as well:
- Specialized software features for point-in-time copy and roll-back
- Failover mechanisms to deal with IP address and in some cases MAC address takeover
- Administration specific to NAS
- The risk-reducing feature of not allowing "other" software to be loaded and executed
- A few vendor-specific capabilities
Yes, you can use a standard server as a file server for NFS, CIFS, etc. In the end, you are providing remote file serving with both types of solutions. A NAS device or appliance was created to reduce cost (primarily in administration), risk and installation simplicity. There's a lot more to consider than just the backend file system used.
Evaluator Group, Inc.
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This was first published in May 2002