Early storage area network (SAN) adopters are now leading another technology charge -- this time to consolidate multiple SANs into one.
While money is on every IT manager's mind, the impetus for consolidation isn't about cutting implementation costs. The new SAN fabric, usually needed at the director-level class of switch to accommodate all the SANs it's consolidating, can cost just as much if not more than the gear it's replacing. The actual savings are in managing the SAN with one software package and one person instead of with several people. The consolidated SAN becomes a much easier environment to manage more effectively.
Consolidated SANs are also ideal for managing different classes of applications. The trick is to use the most appropriate SAN technology for each specific application. A large company's most mission-critical applications will likely require the highest bandwidth and availability of Fibre Channel. Other applications, like backup and disaster recovery or even those on Tier 2 servers, can get by with lower-cost Internet Small Computer System Interface (iSCSI) or Serial ATA.
With the right architecture, one SAN can provide all this functionality. Done correctly, it can lead to some reduced costs, because Serial Advanced Technology Attachment (SATA) and iSCSI gear is less expensive than are the usual high-end storage systems used in Fibre Channel SANs. Which architecture is right depends on the particular performance
"We're starting to see SAN island consolidation used as an opportunity to reduce costs around tiered storage," said Richard Scannell, vice president of corporate development and strategy at GlassHouse Technologies Inc., a storage consultancy in Framingham, Mass.
If there is a down side to consolidation, it's the idea of "putting all your eggs in one basket," Scannell said. But the technology has matured enough that this shouldn't be a problem, assuming proper staff development and training, and the right architecture and processes in place. Plus, for a price, any SAN can be set up to be redundant from the start.
Getting the most of a consolidated SAN requires a different set of processes than managing many separate SANs. Customers are wise to consider these differences before the new SAN is brought in-house, Scannell said.
Indeed, the management differences have been the primary benefits of a SAN consolidation project started two years ago at Oslo, Norway-based EDB Business Partner ASA. The company, which houses Norway's largest data center, develops and operates IT solutions for financial services and telecom clients.
BØrre Christian Børresen, EDB's IT operations manager for storage/SAN infrastructure and services, said his firm replaced five separate Brocade fabrics with one huge director-class and several edge fabrics, all from McData Corp.
"We couldn't grow, and it was very difficult to do SAN management," he said. The company had to use different software for different applications, which in turn required more manpower to maintain.
For that reason, it was time to make a change. Over the past two years, EDB has been slowly connecting its 250 servers to the McData environment, with a few stragglers left to go. "We operate 24/7, so we can't have any down time," Børresen explained.
The answer was to incorporate dual host bus adapters (HBAs) for each server -- one to connect to the old SAN and one to the new. Once everything on the server is migrated over to the new environment, EDB staffers simply move the old HBA connection to the new and then have redundant HBAs for the new SAN.
Børresen declined to provide specifics on the costs involved, but said one big advantage is being able to use the same number of people to manage even more storage. Over the past two years, as the new environment has been brought in, the number of servers and the amount of storage connected has grown by around 50%, he said. They now manage some 200 terabytes of online data and 2 petabytes of other storage, primarily tape.
The move required some training on the new management software from EMC Corp. -- about five days per person. But "it's been all upside for us," said Børresen.
With all this experience, Børresen offered some advice to those who are considering the SAN consolidation route. First, it's not a good idea to mix-and-match SAN components from different vendors because of the management issues. EDB bought the entire new SAN setup from EMC because that is the firm's major disk supplier. (EMC resells McData switches.) While there may be some price advantage to playing suppliers against one another, that strategy can backfire when it comes time to actually implementing and managing all this gear, particularly if you're doing it yourself.
The second thing to keep in mind is that all this will take more time than originally estimated, said Børresen. He also advised to have a good project plan.
It's a good thing the major portions of the learning curve are behind them, Børresen said, because EDB has just landed a big customer -- a company he would not name -- "and we're going to have to add 2,500 more servers" to the SAN. "Now that we have all this experience, it should be much easier."
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This was first published in May 2004