Users Debate Backup Trends

LAS VEGAS -- Storage Decisions -- Disk isn't the answer to all backup problems. While disk-based backup improves on tape, it means more research and testing for storage administrators.

A panel at a West Coast Storage Networking User Group (SNUG) meeting here today shared these and other impressions of backup technologies, giving the pros and cons of relatively new techniques like virtual tape libraries (VTL), continuous data protection (CDP), and data de-duplication. And they didn't forget tape, either.

At least two members on the panel say they're sticking with tape -- for now.

Charles Shepard, director of systems architecture at the MGM Miragecasino group, appreciates disk-based technologies for disaster recovery but remains a big tape fan for long-term backup and archiving.

"We still have a good return on investment for tape," he says. "It's still cheaper than disk. For us to put everything on disk now would be too expensive."Shepard doesnt buy the concept that disk is more reliable, either. "Disk has spindles, it's a mechanical device," he says. "Those spindles have to turn for you to recover data. I'm more worried about disk than about tape."

Rich Taylor, senior systems programmer for Clark County, Nev., disagrees, saying VTL is faster, and tape's frequent format changes make it less valuable for long-term retention.

"If you have a warehouse full of last week's tapes and this week's tape drives, you have a problem," he says.

Marcellus Tabor, manager of storage and data protection at Yahoo, actually agrees with both. He considers VTLs a better way to back up, but found the financial figures didn't justify his plan of getting rid of tape completely.

"I came to Yahoo with the 'tape sucks, I hate tape' attitude," he says. "I said, 'A large portion of our data is short retention, why don't we just put this on VTL and get rid of the large operation headache of moving tapes in and out?' "Tabor's plan of putting tape on the scrap heap ended after the company did a cost analysis. It took account of hardware, software, power, space, cooling, and manpower and found tape was one-third the price of VTL.

Yahoo uses some VTL, but for now, tape lives on. "We wanted to replace all of our tape, but tape still comes out considerably cheaper," he says.

Despite failing to dislodge tape in favor of all VTL, Tabor says he still likes virtual tape better from a technology standpoint. "I'm a big fan of VTL," he says. "It's more reliable. With tape, if a robot fails during your backup, you're done for the night. You don't have that with VTL."

Taylor added: "I think of VTL as fast tape, it's a lot faster than tape. VTLs have saved us because our storage is growing out of control."

Even tape advocate Shepard won't rule out VTL. "We've looked at VTL, we just haven’t found a home for it," he says.Qualcomm storage manager Paul Ferraro is also looking to replace tape down the road, but he suggests a combination of tape and VTL can be a more economical way to go. "With the new LTO-3 format, you can put more data on a cartridge," he says. "You can have fewer [tape] drives and with some disk, it can be a cheaper alternative."

While VTL is the disk-based technology the panelists were most familiar with, CDP and data de-duplication are on their radar screens.

Shepard was the biggest advocate of CDP on the panel. "We use a lot of CDP. We have to have immediate availability of data. With us, it's 24 by 7 by 365 days a year that we don't go dark. We use CDP for disaster recovery." Shepard says CDP enabled his company to bring back data from a casino that went off line.

The others were less enthusiastic about CDP. "It's not a big requirement for us to capture every little change," Ferraro says. "The one place we have that requirement is for databases, but we already have a lot of copies of every database."

Taylor agrees he doesn't need CDP. "For us, CDP now is snapshots," he says. "We don't do any real-time replication. Maybe someday.Tabor doesn't use CDP yet either. "I hold out hope for CDP to be a mechanism where you can tackle large volumes with millions of files," he says. "It's not there yet."

As for data de-duplication, Ferraro was the only member of the panel to take a close look at it. He says Qualcomm is testing it to see how much of a CPU hit it will have. He isn't sure that data de-duplication is the answer for all data in any case.

"Some of the data de-duplication technologies, they're cool and they do work," he says. "But the problem with data de-duplication is, you can't do 500 Tbytes of data and say, 'I want to keep it forever.' "

He has another caveat for de-duplication: "Maybe it's supposed to be duplicated. There may be instances when you want duplicate copies."

— Dave Raffo, News Editor, Byte and Switch0