Virtual tape libraries on the way out, experts say

Disk-based backup has taken a huge step forward in recent years with the advent of the virtual tape library (VTL), but the technology may already be on its way out, according to some users and analysts.

"In the short term, the need to emulate tape is important," according to Jeff Machols, systems integration manager at benefits provider CitiStreet, a subsidiary of Citigroup and State Street Corp. "Long term, I see the need to emulate tape diminishing; the actual emulation of tape and robotic libraries was merely a way to get in the door for the VTL."

The appeal of virtual tape libraries, Machols said, is that companies can add disk to their backup process without having to change their backup software, scripts or procedures, all of which were originally designed to write to tape. Now that disk-based backup is becoming widely accepted, "the software companies are the ones [that will] be running to catch up," he said. "Organizations are going to want to start taking advantage of more and more disk-to-disk functionality and will probably be willing to switch software if one product has a richer feature set supporting disk-based systems."

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For that very reason, Machols said his company has gone with a VTL from Sepaton Inc., which doesn't write to tape at all. For off-site data protection, the Sepaton VTL allows replication to an identical VTL box in another location, he said.

Mark Stewart, backup administrator at Randolph Air Force Base in Texas, agreed with Machols that long-term archiving on tape can be a pain. "One must migrate data from media format to [media] format as hardware upgrades occur," Stewart said. Generally speaking, there will probably always be users who stick with tape; therefore, there will always be backup software companies that gear products toward writing to it. And as long as that happens, VTLs, as we know them, will have a role to play.

But the virtual tape libraries on the market today are in for many changes, according to W. Curtis Preston, vice president of data protection services at GlassHouse Technologies Inc., Framingham, Mass.

"Any company that only offers VTL without any other functionality, like deduplication, will cease to exist within a year or two," he said. "But the VTL companies we have now, like the Sepatons, FalconStors [Software Inc.] and Diligents [Technologies Corp.] of the world, will continue to evolve and exist."

The emulation of tape, according to Preston, is just one way the disk-based backup platform can communicate with the backup application and represent "the backup as files that make sense to the backup application."

"Basically, you have this tarball sent out by the backup application, with files in its own proprietary format … What new backup targets will be able to do is reorganize the data so that it can be easily accessed for restores and put it into a format that can be read by other applications."

According to Preston, several vendors are already working on new disk-centric forms of "intelligent backup targets." Diligent and Sepaton have plans in the works for presenting backups as a reconstituted organized file system, he said, with announcements beginning later this year. Diligent and Sepaton declined to comment.

This new class of intelligent backup targets could have a profound effect on the day-to-day life of backup administrators. "In the future, users may be able to use a Web interface to drag and drop from the backup target to do recoveries themselves," Preston said.