In Praise of Optical Storage

Storage vendors may be beating their marketing drums over disk and tape, but it may pay for users to look beyond these technologies to optical disk. Such was the case for the South Central Veterans' Administration Healthcare System in the aftermath of the hurricane Katrina devastation in New Orleans in late August 2005.

Like many organizations, the South Central VA relied heavily on disk and tape for its backups, although it was optical disk that came to its rescue after the storm.

Speaking during a presentation at Storage Networking World last week, Kenneth Allen, the systems imaging technology manager, explained how the organization struggled to access 9 Tbytes of patient image data on its VistA database after Katrina.

"If there had not been any optical media, there would have been a lot of VA patients now without their [medical] images," he said, explaining that the optical media helped him salvage key data from the organization's New Orleans hospital.

The VA's Medical Center is located in downtown New Orleans, where 6-foot floodwaters seeped into the building after the hurricane struck. "Most of our utilities were down, including the fuel tanks for the emergency generators -- we had nothing," said Allen.A locked room on the second floor held the hospital's storage infrastructure: a RAID array, a Kodak jukebox for optical media, and an HP StorageWorks tape library for backup.

Prior to the hurricane, the hospital successfully backed up a smaller database containing patients' basic data onto a couple of DLT drives, which were sent off to Houston. But the VistA database proved problematic.

"The VistA patient images were too large to back up in time for the storm," said Allen, explaining that his team had to leave the data in New Orleans when the hospital was evacuated.

More than a month later, when Allen returned to the hospital, he expected to simply access the data on the RAID array, but was confronted with an IT manager's worst nightmare. "The RAID drives were gone," he said, explaining that the equipment went missing after local police secured the facility. "The police physically removed the drives, put them in a box, and took them 'somewhere safe.'"

Backup tapes were also hard to come by. "I found one incremental backup dated from April 2005," said Allen.The only media left comprised around 1,250 optical drives for the Kodak jukebox from the likes of Plasmon and Sony, but even these were not in great shape. "There was dust [on the media and] there was some sort of film on there -- I dont know where it came from," said Allen.

He and representatives from Plasmon and Sony went to work for about eight weeks cleaning up and reading the optical disks. By late 2005, only six disks remained unreadable. At this point, EMC Legato stepped up, volunteering to help the VA out by running software on the disks to extract patient data.

Ultimately, the VA managed to retrieve more than 99.9 percent of its patients' image data. Lesson learned? Optical disk has its place in the storage hierarchy. And IT managers need to think outside the limitations of traditional storage setups. In this case, optical drives, not always part of a regular SAN archiving scheme, rose to the challenge. "DLTs are not going to last 75 years, RAID drives will not be readable in 75 years, but optical media will survive 75 years," said Allen.

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