At a high level, a NAS can be described as a multiprotocol network storage appliance with an operating system optimized for file services. One of the advantages of a NAS over a traditional PC-based file server is that it can also act as a Fibre Channel or iSCSI storage array. This means it can present network share via CIFS or NFS like a PC but also give access to disk storage like disk array via iSCSI or FC. NAS appliances also come with data protection software features such as snapshots and replication.
If an organization already has a central storage array or a storage area network (SAN), it is possible to deploy a NAS gateway as an interface to some of the SAN disk and present it as CIFS or NFS shares. If you do not have or do not plan to implement a SAN but still need central storage capabilities, a NAS appliance is the way to go as it is more scalable than most PC-type file servers. If you only have a requirement to share a small amount of data on the network, a PC-type file server will likely be more cost effective.
This was first published in February 2007