The iSCSI protocol is a method of connecting disk storage over a TCP/IP network. It’s rapidly gaining market share in the SAN market because, unlike traditional Fibre Channel systems, it can work over existing IP networks. Like the name implies, much of the protocol is derived from the traditional SCSI interface. Just like SCSI disks, the iSCSI protocol exposes a disk drive directly to the client accessing it; this in contrast to Network-Attached Storage systems that present a ready-to-use filesystem.
Computers or servers that want to access storage systems are called initiators in iSCSI terminology. Because iSCSI runs over TCP/IP networks, the initiator can be implemented in software; most current operating systems include a software iSCSI initiator. There are also special iSCSI HBAs (Host Bus Adapters) that combine a network card with special hardware that offloads some of the processing involved, lowering CPU usage and improving processing speed on the client system.
Dell EqualLogic: an iSCSI storage target
The storage system that’s being accessed is called the target. Targets can be specified in various ways; Wikipedia has some excellent examples that I won’t repeat here. Authentication can be dont by using the CHAP protocol, or by various other authentication systems such as IP-based access control and the use of VPNs and VLANs. While it’s possible to have iSCSI traffic running across a traditional ethernet network alongside other data, using VLANs or VPNs to separate the iSCSI traffic is highly recommended; iSCSI does not provide any encryption, so data is sent in clear text between the initiator and the target.
Your RSS reader
Daily e-mail
Twitter
