Three years ago, the Justice Department faced a difficult dilemma. The number of servers the agency had to back up was expanding, but IT felt that adding to their physical tape library would not be a cost-effective solution.
“Adding more tapes would have been expensive,” says Roger Beasley, the department’s deputy CIO for Operations.
To make better use of his budget and improve the speed and efficiency of backups, Beasley and his team turned to a virtual tape library (VTL), a disk-based technology that emulates pools of storage as tape-based drives. Virtual tape libraries can be software- or appliance-based and are available from manufacturers such as EMC, Fujitsu, HP, IBM, NetApp, Overland Storage, Spectra Logic, Sun Microsystems and Tandberg Data. VTLs enable IT to manage storage as a single entity and run concurrent backups to speed backup and recovery. Rather than mounting and searching through physical tapes, VTLs offer faster and more reliable access to disk-based data.
“VTLs appeal to organizations that are used to dealing with tape because they offer tape-based functions without having to swap and rotate tapes,” says Deni Connor, principal analyst at Storage Strategies Now. VTLs are also budget savers, she adds, because they eliminate the data center footprint of physical libraries as well as the cost of tapes.
Beasley agrees. “It was more efficient to put a VTL in front of the tape drives,” he says.
Federal agencies also like the flexibility VTLs offer. “You don’t have to worry about how much data you can fit on a cartridge. You can size the volumes to whatever virtual tape you want them to be,” says Lauren Whitehouse, senior analyst at the Enterprise Strategy Group. In addition, IT avoids the hassle of drive failures and corrupt backups. They also can recover files faster because they don’t have to recall a tape, load it, and search through to find the point where the data resides.
Whitehouse adds that in many cases VTLs can shorten backup windows, ensuring that backups don’t spill over into the workday and affect network performance.
The Justice Department deployed one VTL to back up Unix and Windows systems and another for its mainframe. The VTLs are interoperable with the department’s IBM Tivoli Storage Manager backup and recovery management software, so IT can use the same backup policies it created for the physical tape library.
50% Public and private-sector organizations that keep their data on a virtual tape library for two months or longer
Source: Enterprise Strategy Group
The VTLs act as secondary storage for almost 700 systems throughout the agency, and data is regularly backed up to tape for continuity of operations. But Connor says many IT leaders have found that they don’t need their physical tape libraries anymore because the VTL can hold enough data. Beasley says he hopes to someday take advantage of site-to-site replication between multiple VTLs for more efficient continuity of operations and disaster recovery.
Beasley also hopes to turn on some of the advanced features of his VTLs, including data deduplication, which he is testing now. Data deduplication is a process by which only changed data is stored and is available in two varieties: in-line and post-processing. Connor says the benefit of in-line, which is offered by IBM, is that you don’t need extra storage to hold the data while it’s checked for duplication.
However, in-line processing can affect performance as bits are checked at the source in real time. With post-processing, which is offered by HP, all data is sent over and then examined at the storage target.
“So far, we’ve only done basic backups with the VTL. The next system we purchase will definitely be full-featured,” Beasley says.