Smaller Vendors Lead
Smaller vendors, such as EqualLogic, StoneFly Networks and Intransa, both based in the US, have taken the lead in offering iSCSI target storage, while larger players such as EMC have offered iSCSI ports on Fibre Channel SANs and multiprotocol switches.
But native iSCSI storage arrays are less expensive, and early buyers are deploying them to support e-mail and database servers, backup and other departmental applications that don't require the high I/O that Fibre Channel delivers-and that won't support the cost of Fibre Channel SAN switches and host adapters.
Now Tier 1 vendors are jumping in. IBM, which withdrew an early iSCSI array, has returned to the market with the TotalStorage DS300. EMC recently announced new Clariion AX and CS Series models that offer native iSCSI connectivity to Fibre Channel, parallel ATA or SATA disk arrays. Every major vendor will have a native iSCSI SAN offering by year's end, says Gray. That's important to users such as Robert Stevenson, a technology strategist at Nielsen Media Research in New York. "Initially, we were very cautious about moving into the iSCSI space [because] the larger players were dismissive of it," he says. But like Tarala, he found the cost and manageability benefits outweighed his initial concerns.
Stevenson started last year with an IP5000 iSCSI target array from Intransa to support a virtual tape library application, then he added another unit to house small Sybase databases that sit behind Nielsen's TV ratings system applications.
A third IP SAN from EqualLogic is in the lab as part of a project to host a larger data warehouse. At about US$3 per gigabyte, storage on the Intransa system is "very economically compelling," Stevenson says.
With more than 10TB on iSCSI-based storage, Stevenson's biggest concern now is rolling administration of those systems into the storage resource management tools that control the rest of his 1.2 petabytes of networked storage. Unfortunately, his current tools don't fully support iSCSI.
Management of iSCSI SAN systems has trailed behind hardware and infrastructure development, and standards like the Storage Networking Industry Association's (SNIA) Storage Management Interface Specification have yet to catch up.
Support for mixed environments like the one Stevenson is considering are an even bigger challenge. "How do I manage an end-to-end environment when the iSCSI host may be several hops away on a Gigabit Ethernet switch or IP router and the proxy Fibre Channel target is on the other side of a multiswitch SAN?" he says.
But those concerns aren't stopping users from creating stand-alone IP SANs to target specific applications. For example, Siemens Corporate Research, added an iSCSI interface to its Network Appliance filer to back up its IBM Rational ClearCase change management software. ClearCase wanted to issue block-writes to direct-attached disks; an iSCSI interface allowed the storage to be migrated to the filer, where it could be backed up using NetApp's Snapshot technology. "The entire [800GB] backup takes less than two minutes," says Ramesh Viswanathan, director of computer and network administration. Adding iSCSI support required a simple, free download from NetApp.
"We didn't have to invest in new hardware," he says.
Bruce Waslie says moving a SQL Server database on an IP SAN can reduce administrator headaches. Last summer, a rapidly growing SQL database that served an imaging application hit 90% of capacity, says Waslie, senior systems engineer at Koch Logistics, a transportation and distribution services provider. Expanding the direct-attached arrays was sometimes problematic and required taking the system down after hours.
Waslie moved the data onto three iSCSI-based Network Storage Module 150 appliances from LeftHand Networks. "The last time I had to expand [storage], I did it in minutes-and I didn't have to come in on a Sunday," he says.
Still, experienced users have other reservations about IP-based storage-especially with regard to the IP network. Waslie isolated his IP SAN traffic on a physically separate network for security and to allow for out-of-band management.
Stevenson says project planners should make sure sufficient bandwidth is available on the existing network before adding iSCSI traffic. And adding IP SAN devices, which require static IP addresses, also increases complexity. "These static IP connection points make it very different to upgrade the storage frames in a heterogeneous environment," he says.
While iSCSI is gaining ground for backups and second-tier applications, Stevenson already envisions using IP SANs for a more mission-critical application at Nielsen. His group wants to create a copy of a 40TB data warehouse for the development team, but without spending US$4 million on a Fibre Channel SAN. "You can get cheap blade servers and get iSCSI to them and put it on SATA [disk arrays], and you've got low cost," he says.
As Nielsen eventually migrates to 10 Gigabit Ethernet, Stevenson expects IP SANs to move still higher into his tiered storage architecture. Even today, he says, "it tends to perform at a higher tier than you would think."