Network attached storage (NAS) generally refers to storage devices that can be attached to the existing corporate network, making NAS pretty cheap to implement. But corporate networks usually run according to Internet protocol, which sends data willy-nilly or in a structure known as file format (e-mail and Word documents are examples of file format). But storage data is generally sent in block format, which requires that the data be sent in a certain order. Storage data does not generally take kindly to being sent in file format. And sending storage data over the company network can seriously slow network speeds.
Internet protocol (IP) storage is a transport mechanism that seeks to solve the aforementioned problem of sending block data over a regular network. Using IP technology to transfer storage data in the block format it prefers, IP storage can save money by allowing a company to use its existing network infrastructure for storage?but it also raises the same performance issues as NAS.
Storage area network (SAN) bypasses sending data over regular networks by building a separate network just for storage devices, servers, backup systems and so forth, and then connecting the SAN to the regular network. SANs may be based on an industrial-strength connector such as fibre channel, which can handle the heavy bandwidth demands of storage data. Keeping storage data off regular corporate networks does lighten the traffic load, but SANs are both expensive and complicated to construct.
Storage virtualization software cajoles different storage devices to interoperate despite the fact that the various operating systems manage storage differently, are set up according to each maker’s technical protocol and cannot communicate with each other. Storage virtualization schemes create a separate layer of software that acts as a universal translator. For example, you can have a pool of storage from Compaq and a pool of storage from EMC, and you’ll be able to move data back and forth between the two.