When it comes to storage technology, Ken Walters doesn't think of himself as avant-garde. "I tend toward the conservative," he says. As the senior director for enterprise platforms at the Public Broadcasting Service in Alexandria, VA, the umbrella organization for 300-plus local PBS broadcasters, "my job is to wear a belt and suspenders," says Walters.
But for a conservative guy, Walters did something pretty cutting edge. In November 2002, Walters implemented an iSCSI network to complement his three-year-old Fibre Channel (FC) storage area network (SAN). The product, the Storage Concentrator from StoneFly, provides an IP bridge into Walter's existing IBM Shark and FastT arrays.
The decision to try out iSCSI came about because according to Walters: "I wasn't making much progress toward consolidation." It's a familiar story: It's hard to justify the cost of FC host bus adapters (HBAs) and switch ports for a $2,000 or $3,000 Linux server.
Walters considered Cisco's SN5420 iSCSI-to-FC router, but ultimately chose StoneFly's product for its virtualization capabilities. "The Cisco product is really a pass-through device--there's no special software, and every LUN still has to be provisioned on the array," Walters says.
"What I wanted was something to help me provision my Shark," he adds. With the Storage Concentrator, Walters simply assigns it a large LUN, which it divvies up to clients.
How's it going for Walters? So far, so good. To date, he's installed seven Windows and Linux servers to the Storage Concentrator, which he upgraded in September to a two-node failover configuration. The iSCSI-enabled servers are running on a Cisco Gigabit Ethernet VLAN, sharing bandwidth of about 50MB/s. Walters has also foregone iSCSI adapters and TCP Offload Engine (TOE) cards, settling on generic $150 Gigabit Ethernet cards.
One surprise has been how stable the iSCSI installation has been. "I'd had my share of things not working on the Fibre Channel side of things, believe me," he says. Not so with the iSCSI network. "I was expecting to have trouble, but I never did." In fact, "I don't remember the last time my network went down."
As far as iSCSI's limited performance, it's all relative. "It's not like I put my mission-critical ERP systems up there," Walters says. Before deploying Storage Concentrator, Walters tested his network using Intel's Iometer utility to determine his bandwidth needs. That testing paid off. "I don't have any performance problems, because I know what my limits are," he says.