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Redundancy and security
INTEC bought two Cisco Catalyst 3550 switches and two Cisco 5428 storage routers for redundancy in its IP network. "We did some absolutely rigorous tests from the standpoint of user and server access," Warlick says. "What does a user see if the router fails, if the drives fail? We tried every failure you can imagine, and the test results were phenomenal. If we turned off one of our switches, that would delay the server connection for a few seconds. But you'd still see the data."
Some customers say they're not too concerned about redundancy from their IP SANs. "I'm not trying to re-create the high availability of a FC SAN," PBS' Walters says. "If I need the ultimate in load-balancing and failover, the application belongs on Fibre," and not on IP. Indeed, if you try to design the same level of redundancy and security into IP, you start to erode some of the cost benefits of the technology, he says.
With PBS' clustered StoneFly gear, however, that level of redundancy is already built in. "I pulled the power cable, NIC cables--I powered them off, and the machine never lost a beat," Walters says. Unlike Fibre, where "I'd be lying if I said we didn't have problems. Fabrics can collapse due to hardware problems; sometimes multipathing doesn't work and you lose your connection to the [Fibre] SAN," Walters says. "If you ask people and they're honest about it, they'll tell you that in practice there
Another suggestion Walters has for redundancy in an IP environment is to put in multiple NICs and run multiple drops to different IP switches. It doubles the NIC costs, but it's still less expensive than going with all Fibre, he says.
On the security front, "eventually we'll be able to use IP-based authentication, but it's not quite there yet," says Sandia's Chen. "Password-based security isn't good enough for us."
But for most users, putting the IP SAN on its own VLAN--and using whatever built-in security comes with their associated products--seems to be good enough. HomeBanc is using the security model that already comes with its PeerStorage SAN. With that, "you have to enter passwords, not just set up a workstation and run the iSCSI initiator and connect," says Woolfolk. "And because it's on a separate VLAN, you can't just hit the PeerStorage box from anywhere on the network."
At Zenon Environmental, Eveleigh says, "Because it's a separate network, it's not exposed to anything. It sits behind the servers, so if someone plugged into our network, they wouldn't see the storage side."
"Most people don't worry much about security," Walters says. "You'd have to break into my DC [data center] to get anywhere near the Fibre network. IP is much closer to the hackers, so maybe we do need to start worrying about it."
Driver and other problems
Most of the issues with drivers seem to be resolved with Microsoft's iSCSI Initiator. But that only works with newer versions of Windows--after Windows 2000--and the Linux and Unix worlds don't yet have this same level of standardization, customers say.
The museum's Wolfe says he's looking forward to implementing LeftHand's new Linux drivers as a way of driving even more IP storage in his shop. "But I doubt they'll ever have direct support for Irix," also used at the museum. In general, the more homogenous the environment, and the more up-to-date the operating system, the fewer problems encountered on the driver front. But there are other kinds of things that bite customers, too.
Stan Rehfuss, senior system admin at the museum, says that with the Cisco 4507 switch, the 48-port cards are set up in a way that you need to distribute your gigabit ports or else you don't get the full gig for performance. "It's just a limitation on the 4507," he says.
Clifford Chance ran into problems, all of which "are behind us now," Morgan says. The firm wanted to mirror its DAS to a cheaper ATA system, so they bought a StorageTek ATA box. "We mirrored the data, and found that after 10 days the server abended," he says. "So we went to Novell and found there was an issue with the way that NetWare 5.1 worked with IP--it didn't. Version 6.0 worked, but we were in the process of moving to NT file storage." Once they moved to NT, it worked fine. But "the issues on the Novell side forced us to increase the pace of a planned migration that was already in progress to Windows NT," says Morgan. Another problem area was implementing jumbo frames on its Cisco switches, to allow more data to be moved at one time.
"When we did that, we had to enable jumbo frames on both switches," says Morgan. "But then that affected other network traffic. It may be the hardware we're using, or it may be the version of Cisco IOS that we're on. But the only solution we came up with was to disable jumbo frames on our main production switches, and then move the IP SAN to its own, separate, much smaller switches." And not everyone's run into problems on that score, either. Zenon Environmental enabled jumbo frames with no problems on its Dell Gigabit switches, Eveleigh says.
Overall, Eveleigh and the others say they're happy they invested in IP SANs. Most of the customers who bought IP for primary storage plan on expanding it to handle backup and restore--and vice versa. As Eveleigh says, "Once you set it up, it's not that fancy a technology. It does its job. I don't worry--and that's a good thing."
This was first published in April 2004