Tale of the (Virtual) Tape

Xwave uses a lot of tape partly because it is a services organization. Customers pay different rates for data storage according to the media used. Tape is cheaper than disk, so many customers choose to put as much of their data on tape as possible, says Craig Piercey, senior technical analyst and team lead in the mainframe technical and DBA database support group of Xwave’s parent company, Aliant Inc.

Since 1999, in three stages Xwave has reduced its vast tape holdings to only about 3,000 tapes, freeing floor space in the data centre to accommodate an expanded server farm and allowing a move to a smaller tape storage vault rather than a larger one.

Virtual tape technology has accounted for the majority of the savings.

The first step in rationalizing the tape glut came in 1999, when Xwave bought a robotic tape library. Serving the company’s mainframe, the tape library uses high-capacity cartridges, which are more efficient for backups and full-volume dumps than the smaller tapes Xwave had been using before. Weekly backups that previously took hundreds of tapes went down to a dozen or so, Piercey says.

Though it made backups more efficient, the tape library didn’t make much of a dent in Xwave’s space problem. The large tape library took up as much space in the data centre as the system saved in tape storage. So the next step was to virtualize Xwave’s onsite tapes.

In 2000, Xwave installed an IBM Corp. 3494 Virtual Tape Server. This unit can stack multiple virtual volumes on a single high-capacity tape cartridge. That’s where the big savings appear, says Piercey.

“A 3290 cartridge can hold over two gigabytes of data,” he explains, “but some people were putting a four-megabyte file on one.”

Besides using tape much more efficiently, the virtual tape system saves operators a lot of time, because they are no longer constantly mounting and dismounting tapes, Piercey says. That speeds up batch jobs for Xwave’s clients, and it frees data centre operators to do other things.

IBM’s mainframe operating systems were written some time ago, says David Hill, principal of storage consulting firm Mesabi Group LLC in Westwood, Mass., and the way they write to data to tape, while it made sense at the time, does not make efficient use of today’s media. That’s why virtual tape technology has become so popular in the past decade, to the point where by now, “I would be surprised to find a large mainframe data centre that didn’t have it,” Hill says.

Virtualizing tapes used for onsite data brought Xwave some savings in space and time, but there was more to be done. The next step came in 2003 – “there were higher priorities between 2001 and 2003,” Piercey recalls – when Xwave decided to virtualize its offsite tape storage as well.

The need had become pressing, because the company’s server farm was running out of room. “We put in dozens of new servers every year,” Piercey says. “We definitely would have had to knock down a wall, expand the data centre and move about 54 staff to another location.” The number of tapes stored in the offsite vault was also rising by about 1,500 a year. Xwave was soon going to need a bigger vault, Piercey says, “which would have meant a real-estate purchase or lease.”

This time, the company turned to Islandia, N.Y.-based Computer Associates International Inc., now CA Inc. Piercey says he had evaluated the software-only CA-Vtape Virtual Tape System when Xwave virtualized its onsite tapes in 2000, but the company ended up purchasing the IBM product because of a package deal with other products. He liked the CA system, though, so it was chosen for the next stage.

The business case for virtualizing Xwave’s offsite tape storage was based on several factors. Saving floor space was a big one, but others included saving maintenance costs on tape drives and shipping costs for sending tapes off site, plus improved data integrity, improved batch windows for Xwave’s customers and allowing data centre staff to spend more of their time on higher-skilled work.

John Relihan, director of storage solutions at CA Canada, says savings on the cost of tape contributes to the business case for virtual tape, but it’s the time savings that really add up. “I think the largest savings come in when you look at the efficiencies that are generated in the manual processes,” he says. Freeing mainframe operators to do other work is even more valuable when you consider that “there’s not a lot of net new mainframe expertise coming on board,” says Relihan.

The implementation took Piercey about two working weeks, he says – a couple of days of planning working with an expert from CA, followed by installing and implementing Vtape on four production systems at about two days per system.

The IBM virtual tape system had already dramatically reduced the number of tapes Xwave was using -from a couple of hundred thousand, Piercey says – but before implementing CA-Vtape the company still had 20,000 tapes on site and more than 10,000 off site. It has 16 tape units in the data centre, and, Piercey says, operators were touching tapes about 500 times per day.

Today there are only three or four hundred tapes left in the data centre and about 2,400 stored offsite. Xwave cancelled maintenance on its 16 tape drives as soon as CA-Vtape was installed, and is now removing the units. And operators touch about 20 tapes a day.

What the benefits add up to for Xwave as a service provider is more efficient storage management and therefore lower costs, Piercey says, “which, in the end, helps us provide quality service at competitive prices.”

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Grant Buckler
Grant Buckler
Freelance journalist specializing in information technology, telecommunications, energy & clean tech. Theatre-lover & trainee hobby farmer.

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