iSCSI represents Internet Small Computer Systems Interface. It is a transport layer protocol that works on top of the Transport Control Protocol (TCP). It enables block-level SCSI data transport between the iSCSI initiator and the storage target over TCP/IP networks. iSCSI supports encrypting the network packets and decrypts upon arrival at the target.
There are multiple means of transports that can be used for iSCSI. The most common is TCP/IP over Ethernet, but Remote Direct Memory Access (RDMA) can also be used with iSER, which is iSCSI Extensions for RDMA. If using iSER, the transport is RoCE or InfiniBand, and the underlying network is Ethernet (for RoCE) or InfiniBand (for InfiniBand transport).
There are two major components of iSCSI, which are as follows −
These initiators set the commands into the network packets and instruct them to transfer at the iSCSI target. A software-based initiator is used at the operating system to perform this data packet transport. There are also hardware devices such as HBA (Host-based Adopters) with high-level encryption functionality.
iSCSI target is the storage device that is a local drive to the host system. When data packets have appeared at the target, the set of commands are implemented to disassemble them in the operating system.
There are various features of iSCSI, which are as follows −
IP Routing − One of the important features of iSCSI is that it uses TCP/IP Protocol. TCP/IP enables long-distance IP routing without the requirement for external gateway hardware. It also supports high flexibility and a large storage network environment.
Security − It is used for securing IP traffic in the network by authenticating and encrypting each data packet received in the network.
Storage array − iSCSI targets in a large storage array. The arrays can be free software-based or commercial products. It usually provides unique iSCSI targets for the number of clients or users.
Standard Ethernet − It uses Standard Ethernet, and because of this, it does not require expensive components to be built for this protocol.