A tape library is a storage device which contains one or more tape drives, a number of slots to hold tape cartridges, a barcode reader to identify tape cartridges and an automated method for loading tapes.
Tape backup is typically used for backup and disaster recovery, periodically copying the contents of all or a designated amount of data from its usual storage device to a tape cartridge device so that, in the event of a hard disk crash or comparable failure, the data will not be lost.
A storage-area network (SAN) is a dedicated high-speed network that interconnects and presents shared pools of storage devices to multiple servers. This allows each server to access shared storage as if it were a drive directly attached to the server.
The main benefit to using a SAN is that raw storage is treated as a pool of resources that can be centrally managed and allocated on an as-needed basis. SANs are also highly scalable because additional capacity can be added as required.
Network-attached storage (NAS) is a type of dedicated file storage device that provides devices with file-based shared storage, usually through a standard Ethernet connection.
An important benefit of NAS is its ability to provide multiple clients on the network with access to the same files. Prior to NAS, enterprises typically had hundreds or even thousands of discrete file servers that had to be separately configured and maintained.