By Ann Silverthorn
—Data Domain today introduced a virtual tape library (VTL) option for its DD400 series of disk-based backup appliances. Users now have the option of emulating a tape library over Fibre Channel, in addition to backing up to a file system over Ethernet.
Data Domain differentiates itself in the VTL market by providing capacity optimization technology, claiming a 20x to 50x compression rate. Capacity optimization shrinks redundancies in the backup image, so it takes less disk space to store backup images and recovery is faster than with tape.
"VTLs are [typically implemented as] a protocol interface on top of an existing disk array, which stores every backup as a full image and is expensive," says Brian Biles, Data Domain's founder and vice president. "So most companies use a VTL as a cache on the way to tape, and recoveries are still from tape. Capacity optimization minimizes the role of tape."
In addition, compressed data takes up less bandwidth, so moving the data over a network from the backup site to a disaster-recovery site becomes more feasible. Data Domain's VTL offers support for the Data Domain Replicator, which automatically copies compressed virtual tape images across a WAN to a disaster-recovery site.
More than 70% of the end users recently surveyed by TheInfoPro research firm are using, piloting, or planning VTL implementations. Rapid data growth and the poor performance of traditional tape-based backup systems have made VTLs a priority in many large IT organizations (See "VTLs top users' priority list," on the cover of InfoStor's January print issue).
The Data Domain VTL emulates up to 47 active virtual LTO drives and 100,000 virtual cartridges. Users do not have to choose between the VTL interface or the existing NAS file service interfaces because they can be used simultaneously.
The 3U DD400 Enterprise Series appliances allow users to store up to 200TB of backup data on-site. The appliances continuously verify the recoverability of data to ensure restores can be performed quickly.
Data Domain's VTL has been tested with backup/recovery software from vendors such as CommVault, EMC/Legato, Hewlett-Packard, IBM/Tivoli, and Symantec. A 55TB DD410 VTL is priced from $4,000.