acronyms150

Users stand to gain efficiencies from new storage networking standards. Arif Mohamed guides you through the acronym minefield and explains the benefits to users.

Several storage networking standards and initiatives have emerged over the past few years, some with broad industry support, but all of them designed to make storage networking easier to manage for the end-user.

The storage industry is no stranger to acronyms. These range from the traditional optical storage technology Cold (Computer Output to Laser Disc); and HDD, which represents the traditional Winchester Hard Disc Drive. Then there is the amusing JBod, which stands for Just a Bunch Of Discs.

Added to the pile are new and emerging storage standards including iSCSI (Internet Small Computer Systems Interface); FCIP (Fibre Channel over Internet Protocol); and SMI-S (Storage Management Initiative Specification).

SCSI has been around since 1986, and is a hardware interface that allows up to 15 peripheral devices to be connected to a single PCI board. SCSI peripherals are daisy chained together, and this technology was a precursor to the Universal Serial Bus.

iSCSI is a distant relation to SCSI in that it is a standard for linking data storage devices over a network and transferring data by carrying SCSI commands over IP-based networks.

This is useful to businesses because iSCSI enables a storage area network to extend its reach and be deployed in a local area network, wide area network or an even bigger metro area network.

Sans provide the high performance and reliability required to support business continuity and disaster recovery, and are also used for remote back-up and archiving, remote mirroring, and centralised management. So extending the San can bring these benefits to larger geographical areas.

Essentially, iSCSI - also known as IP San - gives storage network developers much more flexibility.Companies can ultimately gain faster and standards-based data transfer across larger distances.

iSCSI supports Gigabit Ethernet, which means that iSCSI interfaces can connect directly to standard Gigabit Ethernet switches or IP routers that use the widespread TCP/IP protocol, sending IP packets over an Ethernet connection. iSCSI was developed by the IETF (Internet Engineering Task Force) and became an official standard in February 2003.

Storage network trade association SNIA Europe's chief executive Paul Talbut says iSCSI is rapidly gaining acceptance as an alternative to Fibre Channel for building Sans.

"In terms of maturity, iSCSI is not that mature but there are plenty of products that support it. iSCSI is seen as a logical step and complimentary to Fibre Channel: the enabling technology that led towards Sans. iSCSI was the next evolution for extending the reach of Fibre Channel, and is good at tapping into the ubiquitous Ethernet network, and extending Fibre Channel over longer distances."

As well as using existing IP networks, and reaping the financial gains from that, iSCSI  also allows IT departments to use the IP skills they already have in-house, rather than retraining staff to wrestle with the ins and outs of Fibre Channel, says Talbut.

Network Appliance is one of the major supporters of iSCSI in its storage products, selling the Netapp IP San Solution. EMC also sells iSCSI products across its range of storage, including the low-cost Clariion range. EMC Symmetrix DMX, Connectrix San switches, Celerra Nas and Netwin systems also support iSCSI.

Earlier this year, IBM started selling iSCSI-equipped storage, and teamed up with Adaptec, which sells the Snapserver range of iSCSI storage products. A number of specialists also sell iSCSI equipment, most notably EqualLogic, LeftHand Networks, Intransa, Sanrad and StoneFly Networks.

Talbut says, "SNIA Europe is putting a lot of education behind iSCSI, because it has to go hand in hand [with product releases]. But iSCSI has not necessarily been adopted by the broad range of manufacturers."

An alternative standard to iSCSI is FCIP, which allows users to transmit Fibre Channel data over IP networks.

Fibre Channel was typically designed for local Sans, but like iSCSI, FCIP extends the distance across any IP network and offers users the benefits of flexibility, open industry standards, and network extensibility.

Talbut says it is not possible to compare iSCSI with FCIP on a cost basis because people tend to adopt it for architectural reasons. "The customer has a wide variety of choice when it comes to extending their San."

Driven by large enterprise users, particular suppliers in the Fibre Channel industry developed FCIP over the past few years. It is known as a tunnelling mechanism that uses TCP/IP as the transport while keeping Fibre Channel services intact.

"There has not been mass market adoption yet. It is really being driven on the back of the adoption of high-end Fibre Channel Sans, by the high-end enterprises who want to link together high-end Sans across long distances," says Talbut. 

Like iSCSI, the FCIP protocol was developed within the IETF's IP Storage Working Group and was ratified in 2003 a couple of weeks prior to iSCSI. However, it has not seen the same level of support or adoption.

"It is an interesting technology and has been available on the market for some time," says Talbut. "It may be considered proprietary by some, however the industry recognises it as a very useful Fibre Channel technology, and it has its advantages."

The protocol is supported by a number of key suppliers, including Brocade, Cisco, Lucent Technologies and McData.

Lucent sells the Optistar Edgeswitch based on FCIP, and McData supports the standard in its Fibre Channel Sphereon 3000 Series Fabric switches and Intrepid 6000 Series Directors.

Also on the market is the Cisco Fibre Channel over IP Port Adapter Interface for Cisco 7200 and 7400 Series Routers; and McData's Eclipse 2640 San router, which supports FCIP. McData says that within a datacentre, the 2640 router can interconnect San fabrics from suppliers such as Cisco, Brocade or QLogic, a feature which Cisco also claims to have.

Brocade manufactures the SilkWorm Multiprotocol Router which is able to do Fibre Channel-to-Fibre Channel routing, FCIP tunnelling, and also iSCSI data transfer.

Another standard that is seeing growing adoption by suppliers is the Common Redundant Array of Independent Discs (Raid) Disc Data Format (DDF).

The disc storage specification, which acts almost as an application, provides a common format to allow basic interoperability among Raid products.

Talbut says, "This one came about as a direct result of our end-user councils: it seemed ridiculous to them that we cannot take a Raid device or controller and use it in another array, because the format is unique to that supplier." The specification arose from this user frustration.

The benefits to businesses will come from having a common format across different suppliers' Raid products in which to store information on physical discs. It will also enable a basic level of interoperability between different suppliers of Raid technologies, saving costs to some degree but more importantly, making it easier to build storage arrays and migrate data across Raid products.

DDF, as it is known, is currently out for public review with standards body ANSI (American National Standards Institute), having been approved by SNIA members. It is expected to be ratified this year.

A report from ANSI in October 2004 said the companies that stand to gain the most from DDF are "particularly in the SMB, IT, consumer and retail, and internet markets".

SNIA runs an independent Conformance Testing Programme (CTP) for suppliers to test their hardware against a common script.

However, few storage suppliers have incorporated DDF yet, although Dell is part of a DDF team working to standardise the disc format for Raid controllers. Products are expected in 2006.

Dell is also backing another initiative, this one aiming to standardise the management of storage devices. It recently released a series of Raid products that meet Storage Management Initiative Specification (SMI-S) guidelines.

SMI-S provides a way for storage devices to communicate with storage management software, allowing the software to discover and monitor equipment, and also to control it. SMI-S is based on the Common Information Model (CIM) but will be developed much further than that standard.

SMI-S grew from an initiative some time ago by five storage networking suppliers, called Bluefin. The work was adopted by SNIA Europe and retitled SMI-S.

ANSI adopted SMI-S and through SNIA Europe is continuing to develop and expand its reach. The first version of SMI-S allowed users to manage Fibre Channel devices. Then with version 1.1, SNIA Europe extended it to manage i-SCSI components. In the future it plans to extend it to storage components.

Talbut says, "Users can be much more comfortable that their storage equipment will interoperate. Before this, there were not many storage management products, so there was no need for an interoperability standard. Network storage and Sans have not been around for that long. The introduction of a standard is quite timely."

Neal Watkins, head of SNIA Europe's SMI-S initiative, said the benefits to end-users are manifold. "SMI-S provides freedom of choice, reduces management costs, controls software agent proliferation and reduces overheads and complexity.

"The Storage Management Initiative drives four major programmes: creating a storage standard [SMI-Specification], educating the industry and consumer; driving the implementation of SMI-S in suppliers' products, and testing product compliance with the SNIA Conformance Test Program."

The main suppliers backing SMI-S, and there are many, include AppIQ, Computer Associates, Crosswalk, Dell, EMC, Hewlett-Packard, Hitachi Data Systems, IBM, StorageTek, Sun Microsystems and Symantec.

In terms of products, many now conform to elements of SNIA's Conformance Testing Programme (SNIA-CTP) test specification version 1.0.

Products are available from Brocade, Hitachi Data Systems, Cisco, Hitachi, CNT, IBM, Dell, McData, EMC, Network Appliance, Emulex, QLogic, Engenio, Silicon Graphics, Fujitsu, StorageTek, Hewlett-Packard and Sun Microsystems.

SMI-S is an industry success story and an example of how suppliers can work together for the benefit of the user.

On the horizon is another major storage industry initiative called the Data Management Initiative. DMI is in the very early stages but has the ambitious goal of tying together information lifecycle management, data protection, and long-term archiving and compliance into a standards-based framework.

Talbut says, "It is being developed in the US, and it is a big wave that is coming over."


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This was first published in October 2005

 

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