IP storage-area networks got a boost at the Storage Decisions show in New York recently as ardent users said that deploying iSCSI was love at first sight.
Early adopters made it clear that they weren't using the iSCSI protocol as a replacement for more expensive Fibre Channel SANs, but were primarily adopting it for its cost, ease of installation and as a platform to run less business-critical applications such as Microsoft Exchange or SQL Server. Most say they will keep their database and transaction-intensive applications on Fibre Channel SANs.
The iSCSI protocol lets block-level storage data be transported across the IP network. It sits on top of Ethernet and can be facilitated by adding adapters to servers with their own direct-attached storage or by connecting servers and external storage to an iSCSI gateway device or switch.
To implement iSCSI, users can purchase an Ethernet adapter for US$140, put in a server, load a free Microsoft iSCSI driver on it and connect the server through a Gigabit Ethernet switch to an iSCSI concentrator, which can be bought for as little as US$14,000. By contrast, a typical Fibre Channel adapter costs US$1,300 and a Fibre Channel switch costs US$23,000.
A Merrill Lynch/McKinsey study showed that the total software/hardware cost of an IP SAN, which stored 2T bytes of data, is US$77,000; a Fibre Channel SAN of the same size would cost more than US$180,500. Based on the same study, the total cost of ownership of an iSCSI network is US$117,400 compared with US$231,380 for a Fibre Channel SAN.
Ken Walters, senior director for enterprise platforms at the Public Broadcasting Service , is no neophyte to storage. He already has a Fibre Channel SAN consisting of an IBM Enterprise Storage Server (code-named Shark) connected to his servers via a Brocade Silkworm switch. It stores 3T bytes of data.
When he considered expanding his SAN to link a bunch of servers with direct-attached storage, Walters, who runs IT on a nonprofit budget, chose iSCSI.
"The rest of my machines I wanted to consolidate less expensively," he says. "I needed a cost-effective way to get SAN storage to my IBM BladeCenter servers."
Another attraction of iSCSI for Walters was its simple installation. Because the iSCSI protocol runs on top of Ethernet, it behaves, is installed and is managed in the same fashion.
"I never believe a vendor when they say in 20 minutes you can be up and running," Walters says. "In this case, we could."
Walters, who started testing iSCSI in 2002, installed StoneFly Networks' Storage Concentrator i3000, which connects to his IBM BladeCenter servers and consolidates their storage. He runs less business-critical SQL Server, Exchange and Web applications on the blades, which have the Microsoft iSCSI LAN driver installed.
The iSCSI allure
Thomas Reynolds, senior executive director for IS and technology at Idenix Pharmaceuticals, also saw the allure of iSCSI.
Like Walters, Reynolds, who has 12 Windows 2000 servers running Microsoft Exchange, was skeptical of the vendors' claims of easy installation.
Reynolds wanted a highly available network with no planned downtime. He installed LeftHand's iSCSI Network Storage Module, which contains Advance Technology Attachment storage. The Network Storage Modules connects to the IP network; servers on the network can access information via iSCSI.
"We couldn't invest money in SANs, so we chose iSCSI because it is less expensive," Reynolds says. He runs iSCSI traffic on separate segments of the IP network from network traffic.
Michael Davies, chief implementation officer for satellite communications provider Sawtel, is deploying iSCSI for 8,000 clients. He uses Adaptec iSCSI host bus adapters to connect his servers to storage.
Although iSCSI performs at only the speed of the underlying Ethernet network, Davies says the performance of it was just fine compared with Fibre Channel's 2G bit/sec.
"ISCSI was ideal - about a sixth the cost of deploying a SAN," Davies says. "The iSCSI solution performs very well. Data throughput was very high - 90M to 100M bytes per second."
Robert Bellanti, vice president of data center engineering for KeyBank National Association, is another fan of the low-cost technology.
"ISCSI's on our radar screen," says Bellanti, who has not yet deployed iSCSI. "The challenge of the [Fibre Channel] SAN is that host bus adapters are more expensive [than iSCSI], and deploying SANs snowballs the expense. We are looking at less-expensive options."
Bellanti has 40T to 50T bytes of direct-attached storage in his network and 50T bytes of SAN-attached storage on EMC Clariion and Clariion boxes, and HP Enterprise Virtual Arrays and Enterprise Modular Arrays.
Analysts say that one of the biggest drivers of iSCSI adoption is Microsoft's release of an iSCSI driver last year.
"ISCSI deployments are still relatively recent," says Randy Kerns, senior partner for analyst firm The Evaluator Group. "Windows is the sweet spot right now for iSCSI with Exchange and SQL Server."
The Microsoft connection
Microsoft's endorsement of iSCSI was a boon to Network Appliance, whose users can now install Exchange and SQL Server on the company's network-attached storage devices and receive application support from Microsoft.
"A lot of applications such as SQL Server and Exchange [are written to] require direct-attached storage and iSCSI allows that," says Mike Casey, director of technical operations for Cross Country Healthcare. Casey has two Network Appliance FAS940c clusters.
Although users are generally moving away from direct-attached storage, The Yankee Group estimates that some 40% of storage still is attached directly to servers.
"We have an IBM SAN and looked at the cost and performance associated with it, but we found the administration was so much easier on iSCSI," Casey says. "The iSCSI host bus adapters are typically a third of the cost of Fibre Channel. The cabling is all Category 5. The switches are a fraction of the cost."
On the dark side
Analysts say that despite user enthusiasm, there are downsides to the technology.
"Other than Network Appliance, there are no major storage system vendors that support iSCSI," says Tony Asaro, senior analyst for Enterprise Storage Group. He says although EMC's DMX array supports iSCSI, it is too big and powerful a box to house less business-critical applications.
Asaro says that his firm knows of more than 450 iSCSI production SANs. Network Appliance claims 100 of them.
"Like any technology, there is an adoption curve that takes time for the mainstream to embrace," Asaro says. "As the storage system leaders begin to support iSCSI across all their product lines, more customers will consider it as being a viable choice."
IDC says that the iSCSI market will boom from more than US$1 billion this year to US$5 billion in 2007.