Getting real about iSCSi


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Who supports iSCSI?
Operating systems Microsoft has formally

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announced plans to support the iSCSI standard and will begin offering it as free download to Windows 2000 servers and clients and XP clients beginning in June 2003. Vendors such as Cisco, DataCore, FalconStor, IBM, Network Appliance, and others offer their own third-party iSCSI drivers that run under Windows, which allows Windows to run iSCSI. Linux currently offers various 2.1.x.x releases which implement iSCSI Draft 8 that works with existing iSCSI devices like the Cisco SN5400 series. The most current Linux 3.1.x.x releases implement iSCSI Draft 20. On the general Unix front, none of the major vendors have announced a native iSCSI driver for their respective flavors of Unix.

Switches Cisco, Hewlett-Packard, Nishan Systems, and Sanrad are among the vendors shipping products supporting iSCSI, while the major FC players such as Brocade, Inrange, and McData all have iSCSI in their roadmap. Until native OS iSCSI drivers are released and become generally available, third-party drivers need to be used.

Network cards Any existing network card will support any existing or new iSCSI driver. However, to gain full performance benefits offered by the recently ratified iSCSI standard, you'll need a special network card from a vendor such as Adaptec, Alacritech, Emulex, Intel, LSI Logic, or QLogic. These vendors currently offer cards that offload the processing of the TCP/IP stack from the server's CPU onto an application-specific integrated circuit (ASIC) located on the network card.

Storage arrays Network Appliance announced in February 2003 an iSCSI driver download for Windows that interoperates with its F800 and FAS900 series storage arrays. IBM currently ships its TotalStorage IP Storage 200i, which supports the Windows and Linux environments. EMC hasn't formally announced plans for the support of the iSCSI protocol in their current product lines, while Hitachi Data Systems forecasts iSCSI support for their Lightning line of products sometime in 2003. At least three vendors-- EqualLogic, Eurologic, and Huge Systems--are shipping iSCSI compliant storage arrays, while others such as 3PAR, BlueArc, and Raidzone all plan to bring products to market as soon as customer demand dictates.

Tape libraries Currently, Spectra Logic is the only tape vendor supporting iSCSI, though StorageTek forecasts support sometime in 2003. Most tape library vendors plan to take a wait-and-see approach and use some sort of an iSCSI bridge for connectivity. Atto Technology announced in March that its iPBridge 2500 C/D/R will enable iSCSI connectivity to SCSI tape drives.

Clowney sees Tier 1 vendors such as EMC and Hitachi Data Systems going slowly with iSCSI, fearing it will cannibalize their existing FC market. Meanwhile, other vendors such as Spectra Logic, Boulder, CO, and EqualLogic can be much more aggressive in this space because they want to support incremental growth without worrying about marginalizing an existing FC install base.

Bill Peldzus, senior storage consultant at GlassHouse Technologies, Framingham, MA, adds that neither Tier 1 nor Tier 2 storage vendors want to appear to their customers as having missed the iSCSI boat, so most are at least dipping their toe into the iSCSI waters.

One of the first big-name storage array vendors to take the iSCSI plunge is Network Appliance, Sunnyvale, CA. NetApp offers iSCSI support in its current F800 and FAS900 storage arrays, which can be obtained by upgrading its existing Ethernet interfaces to a free second protocol for existing customers on their support plan.

Dell will ship a storage array supporting iSCSI in the summer of 2003. An EMC spokesman said its customers aren't currently looking for iSCSI-enabled arrays. HDS forecasts an iSCSI announcement sometime in 2003 regarding their Lightning arrays. Smaller storage array vendors such as EqualLogic, Eurologic, and CA-based Huge Systems already natively support iSCSI in their arrays, while NAS vendors such as San Jose, CA-based BlueArc and 3PAR, Fremont, CA, are hedging their bets, introducing iSCSI products as soon as they see market demand.

Among the tape library vendors, none of them with the exception of Louisville, CO-based StorageTek expect support for iSCSI anytime soon. While StorageTek forecasts support for iSCSI sometime in 2003, the other tape library vendors anticipate using iSCSI bridges to connect existing tape drives to the emerging iSCSI storage networks until the market demand justifies the need to support it natively. Not missing a beat, Atto Technology, Amherst, NY, announced in March the release of the industry's first iSCSI bridge--the iPBridge 2500C/R/D. This device enables users to connect iSCSI network infrastructures to their current SCSI tape libraries, extending the functionality of tape libraries to iSCSI connected servers.

Where iSCSI fits
For organizations trying to figure out where iSCSI fits on their technology roadmap, here are some logical places to start. Datalink's Robinson recommends starting with applications and solutions where performance isn't an issue now, and won't be if redeployed with iSCSI. Almost invariably the question of performance crops up in terms of what happens when iSCSI runs over IP on an existing Ethernet network card. (See "The iSCSI performance impact," above)

Despite iSCSI's relative newness, Datalink recently completed a couple of pre-IETF standard iSCSI implementations in campus environments using the Cisco SN 5400 line of storage routers and Cisco's associated OS iSCSI drivers. Robinson says the cost savings these organizations experience using Ethernet based iSCSI vs. FC-based SCSI were significant. In the solutions where Datalink has deployed iSCSI using standard NICs, they have found tape backups perform well and run at approximately 70% to 80% of 1Gb FC.

Bryce Mackin, the marketing coordinator for the Storage Networking Industry Association (SNIA) IP storage forum, says it's important to remember that iSCSI's intended audience is small to midsize companies. Always trying to steer a diplomatic course between competing storage industry camps, SNIA views FC and iSCSI as complementary--not competing--technologies. Each, Mackin says, will have strong value propositions for different size organizations.

Storage consultant Toigo sees a lot of value in putting iSCSI networks behind NAS heads. In NAS environments, he says, performance isn't usually the primary concern and by putting NAS heads in front of iSCSI-based SANs is an economical and potentially highly scalable NAS solution. It also mitigates some of the storage and security management issues introduced in multiOS environments.

This was first published in May 2003

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