ISCSI
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- The title of this article is incorrect because of technical limitations. The correct title is iSCSI.
In the context of computer storage, Internet SCSI (iSCSI) uses the SCSI protocol over a TCP/IP network. It enables any machine on an IP network (initiator) to contact a remote dedicated server (target) and perform block I/O on it just as it would do with a local hard disk.
Functionality
The iSCSI protocol uses TCP/IP for its data transfer. Unlike other network storage protocols, such as Fibre Channel (which is the foundation of most SANs), it requires only the simple and ubiquitous Ethernet interface (or any other TCP/IP-capable network) to operate. This enables low-cost centralization of storage without all of the usual expense and incompatibility normally associated with Fibre Channel storage area networks.
Critics of iSCSI expect worse performance than Fibre Channel due to the protocol overhead TCP/IP adds to the communication between client and storage. However new techniques like TCP Offload Engine (TOE) help in reducing this overhead. And tests have shown excellent performance of iSCSI SANs, whether TOEs or plain Gigabit Ethernet NICs were used. In fact, in modern high-performance servers, a plain NIC with efficient network driver code can outperform a TOE card because fewer interrupts and DMA memory transfers are required.
The Internet Engineering Task Force ratified iSCSI as an official standard on February 11 2003.
Industry support
- Initiators
- Adaptec is shipping a TOE NIC
- Cisco has a free software initiator (http://www.cisco.com/univercd/cc/td/doc/product/sn5000/sn5400/iscsidrv) for most Operating Systems
- Intel has funded an open source initiator (http://sourceforge.net/projects/intel-iscsi)
- Microsoft announced its support for iSCSI by providing iSCSI inititators (http://www.microsoft.com/windowsserversystem/storage/technologies/iscsi/default.mspx) in their latest Windows OS and storage server products.
- PyX Technologies (http://www.pyxtechnologies.com) licenses the complete iSCSI protocol software, (including all error recovery levels, mandatory and optional feature sets), to OEMs, developers and integrators.
- Targets
- Cisco bridge
- EMC Corporation
- FalconStor (http://www.falconstor.com) offers Enterprise Integrated IP/iSCSI/Fibre Channel SAN
- HDS
- HP (http://www.hp.com/storage) has a complete set of storage products/services ranging from Small to Enterprise SANs
- IBM
- Network Appliance Filers
- NeuStream (http://neustream.com) has merged ISCSI, NAS, and SAN
- Intransa (http://www.intransa.com) offers enterprise-class iSCSI based IP SAN.
- SANRAD (http://www.sanrad.com) offers an all-in-one iSCSI based IP SAN.
- StoneFly Networks (http://www.stonefly.com/) offers IP SANs for departments, workgroups and mid-tier organizations
- Voltaire Inc. (http://www.voltaire.com/) offers iSCSI/iSER based InfiniBand to Fibre-Channel Routers.
- EqualLogic (http://www.equallogic.com/) offers a storage array that can handle iSCSI traffic from NetWare, Windows, Linux, Solaris
- PyX Technologies (http://www.pyxtechnologies.com) offers a storage engine that can export out any type of storage as iSCSI
See also
- RFC 3720 Internet Small Computer Systems Interface (iSCSI) (http://www.faqs.org/rfcs/rfc3720.html)
- Fibre Channel over IP (FCIP)de:ISCSI