There's no shortage of technologies promising better backups: disk-to-disk (D2D), virtual tape, continuous data protection and D2D to tape (D2D2T). Advanced Digital Information Corp. (ADIC), Redmond, WA, adds another to the list: integrated D2D2T.
ADIC's Pathlight VX 2.0 tightly combines disk and tape in a single appliance that allocates disk and tape in variable proportions, depending on your need for fast performance or low-cost, long-term archiving. The appliance appears as a standard tape backup system to backup software. It uses RAID 3 with an EMC Clariion disk array along with its own internal data management software to automatically move data backed up on disk to an ADIC tape library for long-term retention.
The result is the performance of D2D and virtual tape for backup and recovery, and the flexibility, portability and low cost of conventional tape. Depending on the amount of capacity purchased and the proportion of disk to tape in the appliance, pricing could range from $7.50/GB (45TB system with 3.8TB of disk) to just $2/GB (300TB system with 23.2TB of disk). ADIC says the Pathlight VX 2.0 can scale to nearly 3PB.
The ability to scale to petabytes while mixing the proportion of disk and tape seamlessly keeps costs down. "I like the idea of virtualizing backup as a single system and making it so expandable," says Tony Asaro, senior analyst at the Enterprise Strategy Group in Milford, MA. "By including tape, you drive down total cost and still manage it logically as a single system."
Dianne McAdam, a senior analyst and partner at the Data Mobility Group LLC, Nashua, NH, also likes Pathlight VX's tight disk and tape integration. "The problem with D2D devices has been that there's no clean way to write the contents to tape," she says. Other D2D and virtual tape products typically require export technology and another process to create tapes from the backed up data. "But Pathlight VX automatically moves the data from disk to tape, which eliminates errors," she adds. For now, this makes it unique.
McAdam also likes the way Pathlight VX writes to tape in a non-proprietary format. It creates a conventional backup tape using standard tape media and formats, so you can restore from a Pathlight VX tape using any tape device.
When Pathlight moves disk data to tape, the data on the tape can be restored using any tape reader for that size and format tape. When data is moved from disk to tape, all the data in the data set is moved. It doesn't go back to disk unless it has been restored from tape and backed up again as if it were new data. If you're restoring multiple data sets, you'll likely find yesterday's data set on disk, while data sets from two weeks ago have been moved to tape. In all cases, data is moved based on rules you've defined.
It's tempting to think of Pathlight VX as a tiered storage product combining a near-line disk tier and archival tape. However, ADIC doesn't recommend Pathlight VX for anything other than backup and recovery because you can't access the data on the disk portion except through a standard tape restore process.
Analysts found few drawbacks in their preliminary assessments of Pathlight VX 2.0. There is no mainframe interface, notes Asaro. Quibbles aside, "it's an elegant backup approach," he concludes.
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