Many companies have made a large investment in Fibre Channel and SCSI storage. With the advent of SAS and SATA storage there is now an abundance of both storage technologies. Conversion of these technologies to iSCSI is possible using a bridging appliance. Bridging appliances take one technology and convert it to another to easily adapt to a SAN, WAN or LAN. For instance, the iPBridge 2700 from [[ATTO Technology]], Inc allows customers to attach Fibre Channel devices and then connect them to an IP network using iSCSI. There are also conversions available from SCSI to iSCSI as well as SAS/SATA to iSCSI. This bridging technology allows customers to use their storage in heterogeneous environments while extending existing investments in storage infrastructures ...more


SCSI is a popular family of protocols that enable systems to communicate with I/O devices, especially storage devices. SCSI protocols are request/response application protocols with a common standardized architecture model and basic command set, as well as standardized command sets for different device classes (disks, tapes, media-changers etc.). more


Open-iSCSI project is a high performance, transport independent, multi-platform implementation of RFC3720. more

With the release of the Fibre Channel and SAN based on it the storage world staked on a network access to storage devices.... For several years the FC interface was the only standard for such networks .... At present there are some initiatives which are being standardized; they are meant to solve or diminish the problems. The most interesting of them is iSCSI. more

The Linux iSCSI driver acts as an iSCSI protocol initiator to transport SCSI requests and responses over an IP network between the client and an iSCSI-enabled target device such as a Cisco SN 5428-2 storage router. The iSCSI protocol is an IETF-defined protocol for IP storage ... more

By carrying SCSI commands over IP networks, iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances. The iSCSI protocol is among the key technologies  more

Internet SCSI

Definition: iSCSI or Internet SCSI is pronounced eye skuzzy and is an IP-based standard used for linking data storage devices over a network and enabling the transfer of data by carrying SCSI commands over IP networks.

iSCSI is a TCP/IP-based protocol which enables the transport protocol for SCSI which is operational on top of the TCP. It offers a mechanism for capturing SCSI commands on an IP network. It is a protocol for data storage systems that natively use TCP/IP. Packet delivery with SCSI is different from that with IP. Packet delivery in IP is not in a fixed order.

Since iSCSI makes use of the ubiquitous Ethernet, it offers enormous potential for low-cost centralization of storage.

With SCSI as a channel interface, the packets are delivered in a sequence and a break in sequence can lead to data loss. Also, iSCSI requires a bulkier packet head that contains additional information for speeding up packet assembly. The delay/latency that occurs in data transfer over the Ethernet is one of the main reasons holding back the commercial advance of iSCSI. That said, techniques like the TCP Offload Engine (TOE) are proving useful in reducing overheads associated with the TCP/IP protocol. High Ethernet speeds are encouraging organizations to deploy gigabit and 10 gigabit networks.

The attraction of iSCSI lies in the advantages it offers. These include consolidation of data storage systems; backup of data; efficient server clusters; ease of replication and recovery. IP storage enables the realization of capabilities such as QoS, improved safety and SAN geographic distribution. Storage area systems with native iSCSI offer advantages in terms of providing a single technology that connects storage systems, servers, and clients existing in a LAN, WAN, SAN. Storage systems need not be in geographic proximity to the applications.

With an iSCSI interface, it is possible to transfer data to the storage devices using not only data carriers and communicatorsiSCSI hard disks but also network cards on the client side. However, the use of network cards can consume significant amounts of processor power on the client’s side.

iSCSI is a great way to access disk drives over a LAN. It eliminates the need to buy, deploy, install, learn, manage, and upgrade a new networking infrastructure. Since disk drives themselves do not have Ethernet connectivity, intelligent controllers are used to act as iSCSI target devices so that the SCSI packets transferred through the GiGE cables are converted into a language compatible with the disk drive. The controllers also cache I/Os in the memory so that latencies inherent in the drive are masked.

Major components of iSCSI include:

• iSCSI Address and Naming Conventions. • iSCSI Session Management. • iSCSI Error Handling. • iSCSI Security.

SCSI devices available in a network are identified through iSCSI nodes that are named according to the rules adopted for naming internet nodes. An iSCSI name enables quick identification of an iSCSI device regardless of its physical location.

Session management with iSCSI consists of two phases, a login phase and a full-feature phase. The Fiber Channel Port Login process and the Login Phase of the iSCSI are identical.

The iSCSI protocol provides measures for handling errors because there is a high probability of errors in delivering data over IP networks. The protocol also provides security measures to protect data over networks susceptible to illegal access.

iSCSI security is a major concern with IT administrators because of the easily available Ethernet operable devices. Best practices to ensure iSCSI security include segregating the iSCSI SAN so that the iSCSI storage is not exposed to the open LAN. An iSCSI array should be connected only to the data storage servers and preferably a physically isolated iSCSI SAN island should be created.

iscsi The management interface should be secured to prevent unauthorized access from hackers. This is particularly true with web-based configuration tools that can be accessed from anywhere. Services such as DHCP, DNS, and WIN are superfluous on an iSCSI SAN and should be disabled. Authentication such as CHAP and encryption such as IPSec should be employed wherever required.

The evolution of iSCSI gathered momentum after it was approved as an industry standard in 2003. At present, the majority of the deployments use software-based iSCSI initiators and standard Ethernet NICs; however, there is an increase in the demand for TCP offload enabled (TOE) enabled iSCSI adapters. TOE adapters help manage high traffic storage environments.

Disk server software is available at different price points that cater to environments of different sizes and the type of features needed. With this approach, you pay only for what you use; this makes it possible to start with the minimum software set required for your storage needs and then upgrade when new features are required. An important feature that can be added later is the Fibre Channel host connections alongside the iSCSI ports for higher, more deterministic I/O performance required by larger hosts.

By including software-enabled disk servers in your iSCSI solution, you add to the flexibility and performance of your set-up. You can choose from a range of hardware platforms, price tiers, and extra features that may not be available from purpose-built appliances or arrays.