iSCSI – Universal Protocol For IP Storage
iSCSI is an internet protocol based storage networking standard used in linking data storage appliances. iSCSI stands for Internet Small Computer System Interface and was developed by Internet Engineering Task Force (IETF). iSCSI facilitates carrying of SCSI commands over the IP networks and so offers data transfers over intranet and thus simplifies the management of storage over long distance. iSCSI can be used to transmit data over Local Area Network (LANs), Wide Area Networks (WANs) and can enable location independent data storage as well as retrieval of data.
As soon as the end user application propels a request to the operating system, an appropriate SCSI command and a data request are generated, which then go through the encapsulation phase and also the encryption procedure, if needed. A packet header is added and then the resultant IP packets are transmitted over an Ethernet connection.
When the packet is received, it goes through the decrypted procedure (if in case the data was encrypted before transmission) and disassembling of the packet takes place where SCSI commands and request get differentiated. The SCSI commands are then sent to the SCSI controller and from there they are diverted to the SCSI storage device. It is a known fact that iSCSI is a bi-directional protocol and so it can also be used to return data in response to the original request as well.
Benefits of iSCSI
With the combination of SCSI, Ethernet and TCP/IP iSCSI offers the following advantages
- As it is built on the stable and familiar standards, most of the IT staff are familiar with the technology
- iSCSI involvement will create a SAN which has a reduced Total Cost Of Ownership (TCO). This is achieved as the installation and maintenance costs are low due to the involvement of TCP/IP and hence it eliminates the need for hiring specialized personnel
- As Ethernet transmissions can travel over the IP network there will be no practical distance limitations
- iSCSI deployment offers a high degree of interoperability. So, it reduces disparate networks and cabling as it can be achieved through Ethernet switches instead of the specialized hardware of FC switches which are high on price factor as well