Servers use a high speed interconnect to communicate with their directly attached storage devices called SCSI (Small Computer System Interface). iSCSI (internet SCSI) encapsulates SCSI block storage commands into Ethernet packets for transport over IP networks. This enables servers to communicate with shared storage devices over standard IP infrastructure using standard SCSI storage commands. This allows businesses to easily expand storage capacity and share storage resources across servers.

iSCSI is a new standard for sending SCSI commands over an IP network. It is the networking industry's answer to Fibre Channel. Storage Area Networks are becoming very important to any company that needs large amounts of reliable storage. Fibre Channel is the defacto standard protocol for most SANs. Cisco and other networking companies are now pushing iSCSI since they ignored fibre channel for too long and don't want to be left out of the SAN market.

The iSCSI Consortium is a world class test house for iSCSI products. The consortium brings together members and industry to foster interoperability among iSCSI products and increase the market feasibility of iSCSI technology. Like other UNH-IOL Consortiums, the iSCSI Consortium is fully funded by our member companies.

The software drivers that reside on the servers that access the storage servers via iSCSI and encapsulate SCSI commands in IP packets and use the Ethernet to transport them to the storage servers are called "initiators". The software taht interprets iSCSI commands on the storage server and allows access to storage under its management is called an iSCSI "target".

Operating system vendors have endorsed iSCSI enthusiastically and free implementation of iSCSI initiator drivers are available for most. They include:

Operating system vendors have endorsed iSCSI enthusiastically and free implementation of iSCSI initiator drivers are available for most. They include:

A complete list of the equipment in our test bed can be found on our equipment page. For details on specific equipment, including the software and firmware versions that are being used, please contact us.

Fiber Channel, being a high speed serial interconnect, has no routing and failover capabilities and allows for only primitive address management and security considerations. To overcome these limitations, complex configuration schemes have been devised that require specialized expertise and complex environments. These have made Fiber Channel based solutions inherently expensive to acquire and maintain.

Answer: Storage virtualization is not done at a protocol level: i.e. it is not dependent on SCSI, iSCSI or Fibre Channel. It is done at a disk block level. This means that a virtualization device, like the Data Transport Processor or FalconStor's IPStor, can access storage over Fibre Channel as well as iSCSI and regular SCSI and serve it to computers attached over any of those cables/protocols.

The software drivers that reside on the servers that access the storage servers via iSCSI and encapsulate SCSI commands in IP packets and use the Ethernet to transport them to the storage servers are called "initiators". The software taht interprets iSCSI commands on the storage server and allows access to storage under its management is called an iSCSI "target".

Fiber Channel, being a high speed serial interconnect, has no routing and failover capabilities and allows for only primitive address management and security considerations. To overcome these limitations, complex configuration schemes have been devised that require specialized expertise and complex environments. These have made Fiber Channel based solutions inherently expensive to acquire and maintain.

The primary financial benefit of the iSCSI Consortium is our extensive conformance and interoperability test services; as a member, you can benefit from our expertise and eliminate the costs of developing such tests internally. Our test suite procedures and methodologies have been reviewed and accepted by the member community, ensuring a uniform interpretation of the standard and the implementation of our tests. Also, we have an interoperability test bed of iSCSI devices.

Answer: iSCSI and NFS (Network File System) or CIFS (Common Internet File System - MS proprietary network filesystem) all allow storage access over IP networking infrastructure. However, iSCSI enables block storage transfer while NFS and CIFS transfers files. Ultimately a file is composed at the NFS/CIFS server device through block level storage access. Block level storage access offers superior performance for data intensive software applications and databases.

Answer: Not necessarily, but it depends. iSCSI can be used over a standard TCP/IP link with your existing Ethernet adapter if you have a software iSCSI driver installed. A dedicated iSCSI HBA can improve performance. Some operating systems do not have software-only iSCSI drivers available, in which case, a special iSCSI HBA might be the only choice.

Answer: As of November, 2003, software drivers are available for MS Windows 2000/NT/XP, Linux, Solaris and HP-UX. Here are the links to some of those drivers (in new window):

Answer: As of November, 2003, we know of four manufacturers who have released iSCSI HBA's (in new window): We are not mentioning so called "TOE NICs", or TCP Offload Engines, because they are not optimized to be used as a server's storage peripheral and are generally not supported by major OS manufacturers.

Answer: No, in most cases you do not. One of the major advantages of iSCSI over Fibre Channel SANs is that it utilizes existing IP infrastructure. In some cases, however, it might be desirable to separate storage traffic into a dedicated network for performance reasons. This is especially true for installations which do not have a Gigabit Ethernet network installed. Answer: Yes--In February 2003 the IESG approved iSCSI draft 20 (with two brief modifications) as a Proposed Standard.