Network storage is a generic term used to describe network based data storage. There are three formats of network storage: Direct Attached Storage (DAS), Network Attached Storage (NAS) and Storage Area Network (SAN).

Direct Attached Storage (DAS): it a storage device directly attached to a host system, such as the internal hard drive of a server computer. DAS is still, by far, the most common method of storing data for computer systems.

Network Attached Storage (NAS): NAS is a data storage mechanism that uses special devices connected directly to the network media. These devices are assigned an IP address and can then be accessed by clients via a server that acts as a gateway to the data, or in some cases allows the device to be accessed directly by the clients without an intermediary.

Storage Area Network (SAN): A SAN is a network of storage devices that are connected to each other and to a server, or cluster of servers, which act as an access point to the SAN. In some configurations a SAN is also connected to the network. SAN's use special switches as a mechanism to connect the devices. These switches, which look a lot like a normal Ethernet networking switch, act as the connectivity point for SAN's. Making it possible for devices to communicate with each other on a separate network brings with it many advantages.

The technologies and protocols used in the network storage communications are SCSI, RAID, iSCSI and Fiber Channel. For years SCSI has been providing a high speed, reliable method for data storage. RAID (Redundant Array of Independent Disks) is a series of standards which provide improved performance and/or fault tolerance for disk failures. Fibre Channel is a technology used to interconnect storage devices allowing them to communicate at very high speeds (up to 10Gbps in future implementations). As well as being faster than more traditional storage technologies like SCSI, Fibre Channel also allows for devices to be connected over a much greater distance. iSCSI is a technology that allows data to be transported to and from storage devices over an IP network. What it actually does is serialize the data from a SCSI connection. Using iSCSI, the concept of network storage can be taken anywhere that IP can go, which as the Internet proves, is basically anywhere.

Network Storage Technologies

Related Terms:SCSI, fiber Channel, iSCSI, RAID, SAN, NAS, DAS