Until recently, storage-area networks (SAN) have gotten a mixed reception. Users have praised their performance and flexibility but criticized their cost, complexity and lack of interoperability. But new products based on current standards have finally begun to address those problems. And practitioners who have been down this road say that lower maintenance and support costs can quickly make up for the relatively high deployment costs for SANs.
But IT managers planning a deployment still face some key issues, and practitioners suggest moving cautiously and doing your homework.
Carefully working with vendors upfront and getting the right experts on board are critical success factors when installing a SAN. For example, MasterCard International Inc. had a good deal of in-house expertise but nevertheless brought in a consultant to help get its tape and disk SANs going.
MasterCard enlisted Stamford, Conn.-based Gartner Inc. and other external sources to help it choose Hopkinton, Mass.-based EMC Corp. as the primary vendor for its disk SAN, says Jim Hull, vice-president for computer network services at MasterCard’s U.S. processing centre in St. Louis. The tape backup SAN uses Fibre Channel switches from San Jose-based Brocade Communications Systems Inc.
A tape subsystem from Storage Technology Corp. in Louisville, Colo., backs up 160TB of online storage located in a series of EMC Symmetrix disk arrays and an IBM Shark Enterprise Storage Server. In all, approximately 195 servers access the SAN-attached data, including a half-dozen Enterprise 10000 servers from Sun Microsystems Inc., an IBM S/390 mainframe and network-attached storage devices.
The consultant helped Purchase, N.Y.-based MasterCard ensure that all of the gear would plug and play with its existing IBM Shark disk storage, management software from Tivoli Systems Inc., StorageTek tape subsystems and other components. The consultant got vendor representatives together for some tough meetings, Hull says. “He did not have ties to any vendor,” he says. “He was my hip-pocket resource.”
Getting all the components to work together was tricky, Hull acknowledges. “The standards in SAN technology are emerging as we go,” he says. “The Brocade and [EMC] Connectrix switches were based on two sets of standards that really weren’t standards yet. It looks like within the next year they will play together well, but at the time we did this SAN, they were not.”
Continuing growth in data storage needs is pushing even cautious IT managers to consider SANs. OCLC Online Computer Library Center Inc., a Dublin, Ohio-based provider of digital information to 40,000 libraries around the world, saw its data storage requirements increase by 900 per cent in five years. Data on its Windows and AIX servers grew especially fast as OCLC added new databases and services for its members, says Jerry Lynch, division director for operations.
Seeking a way to accommodate that growth without adding IT staff, OCLC tied together the disk storage for its Unix and Windows servers and its IBM S/390 mainframe with a Fibre Channel SAN consisting of Fibre Channel switches from McData Corp. in Broomfield, Colo., along with IBM Shark and StorageTek V960 Shared Virtual Array (SVA) disk storage systems. In addition to acting as the primary online storage for production servers, the SAN backs up data on 1,200 PCs every night. The disk SAN manages a total of about 4TB of data.
The peaceful coexistence of McData, IBM and StorageTek gear is a tribute to industry standards efforts, Lynch says. “We can plug all three things together, and they won’t catch on fire,” he laughs.
“I had a Shark on the floor, but the best deal [to expand capacity] was to bring in a StorageTek SVA,” Lynch says. “In the past, prior to the Fibre Channel standard, I would probably have been much more apt to put in another Shark. As it was, I was able to get competitive bids from two different vendors.”
Regarding some users’ complaints that SANs are tricky to get up and running, Lynch says, “You have to know what you are doing and have business partners and vendors who you can trust and who are engaged.” But he says improvements in SAN deployment and administration tools are putting SANs within the reach of less-sophisticated companies.
“The past year has seen dramatic improvement,” Lynch says, citing Houston-based BMC Software Inc. in particular. BMC’s Patrol storage management and Mainview storage resource management tools, for example, look at storage from both a physical device and an application point of view, and that aids storage planning and administration, according to BMC.
Bill North, research director for storage at IDC in Framingham, Mass., says storage networks are becoming easier to administer as storage and network management tools converge. For example, he cites EMC’s recent introduction of its WideSky and StorageScope products, which not only monitor and manage EMC platforms but also include interfaces that allow connections to other vendors’ storage systems.
Chuck Kinne, a technology consultant at AT&T Labs in Florham Park, N.J., helped AT&T Solutions install SANs at four locations. AT&T Labs built three of the SANs around Hewlett-Packard Co.’s SureStor XP256 disk arrays and Brocade’s SilkWorm 2800 Fibre Channel switches. Each of those SANs will eventually support 90 servers and 3.3TB of data, Kinne says.
“Now they are all HP, but we’ll add Solaris and NT, and within six months we’ll have all kinds of things attached,” he says.
The best way to avoid interoperability problems, Kinne advises, is to use the latest software releases and make sure all the latest patches are applied, especially to operating systems.
Kinne says AT&T went with HP because it was the first to offer a Fibre Channel boot capability, which allows servers to boot directly from the SAN disk array. “I had no internal disk in any of the servers on the SAN, no direct-attached storage. We do everything in the array,” he says. That makes management and change control much easier, he adds.
But the most compelling benefit of Fibre Channel boot is the reliability it brings, according to Kinne. “Our No. 1 problem with the servers was with the failure of internal disk drives,” he says. “I don’t have to worry about disk failures anymore because there is redundancy inside the array.”
Kinne acknowledges that it was more expensive initially to set up the SANs than to upgrade the older direct-attached storage, but he says storage administration with a SAN costs half as much. “When you add up the cost of outages, time to do conversions, backup and recovery all of which are much simpler with a SAN and then throw in the extra cost of the array and switches, I figure I break even at between 40 and 50 servers on the SAN,” he says. “After that, it’s gravy.”
Kinne’s fourth SAN uses EMC disk arrays instead of HP disks, and McData switches rather than Brocade devices. “It provides a measure of competition,” he explains. “I can say, ‘HP did this; EMC did that. Let’s compare price and support.’ It keeps them both honest.”
You may not need a great deal of expertise to deploy a SAN, says North. “If I’m a neophyte with SANs, I’d work with a company that provides the integration expertise,” he says. “Compaq and Dell package up turnkey solutions for particular business problems. They [offer] single-source, multivendor solutions. And they support them as an integrated package.”
Storage Virtualization: The Next Step
Storage virtualization software may simplify management, but the technology is still immature, practitioners say.
“I’m watching carefully a little company out of Fort Lauderdale, Fla.,” says Jerry Lynch, division director for operations at OCLC. “The user community is going to go nuts for this kind of stuff.”
That company is DataCore Software Corp., and the stuff is SANsymphony, storage virtualization software that promises to tie disparate storage devices including SAN, network and direct-attached storage devices into one virtual storage pool.
Storage virtualization software separates the server’s view of storage from actual physical storage. By presenting storage on disparate physical devices as one central pool, storage management is greatly simplified.
“If we don’t do something about storage soon, we are all going to be storage administrators,” Lynch says. “The way to get around that is to virtualize it and network it so you can mask the complexity.”
“Virtualization creates an abstraction layer between the applications and the physical storage, so it enables simple management of heterogeneous resources,” says Steve Duplessie, an analyst at Enterprise Storage Group Inc. in Milford, Mass. “Virtualization enables true homogeneity, so I can have EMC stuff sitting next to Compaq stuff all working like one seamless thing.” But the technology is immature; products typically don’t yet interoperate smoothly, and although storage virtualization facilitates management, it can adversely affect performance on servers or SAN switches.
Xand Corp., a system hosting firm in Hawthorne, N.Y., has an 8TB SAN and recently installed SANsymphony. Senior Vice-President Joe Fuccillo says he hopes it will facilitate the administration of Xand’s heterogeneous storage environment, make SAN expansion easier and enable asynchronous data mirroring to storage on off-SAN servers.
But he says Xand will proceed with caution. “Anytime you add another layer between storage and hosts, you have to make very sure it’s stable and fault-tolerant,” he says.
“Virtualization dramatically increases the amount of storage an administrator can manage,” says Dan Tanner, a senior analyst for storage and storage management at Aberdeen Group Inc. in Boston. But, he cautions, virtualization products are emerging piecemeal and may introduce interoperability problems.
Tanner also warns users not to confuse the management of storage devices with the management of storage content. “The mainstream of virtualization today applies to storage space, with only a trickle addressing virtual files the objects actually being stored in the space created,” he says.