Government Computer News
Backup to the future
Backup plans: blended storage
The Geographic Information Systems’ department in Pierce County, Wash., needed the best of both worlds—the speed of disk to quickly retrieve data and the cost-effectiveness of tape backups. They found the best approach to be one that blended both tape and disk-backup systems, according to Linda Gerull, Pierce County’s GIS Manager.
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Gerull’s department maintains the geographic data for the county, which is used by 800 users in 25 other departments. The county includes agricultural, high-tech manufacturing, urban (Tacoma) and tourism (Mount Rainier) features—all of which depend on geographic information for planning and management. The department also offers free GIS applications and services on the Web (see GCN.com, Quickfind 737).
Maintaining such data can take a lot of disk space. GIS-based maps tend to be large data files, ranging into the gigabytes. They could be satellite imagery, or 3-D terrain maps. Complicating the task is the availability of new orthophotography and LIDAR (Light Detection and Ranging) data for the area. While undeniably valuable to users, the 2,400-plus files are large and only add to the task of providing information and applications to the public.
Keeping all these different versions of files on disk would be cost-prohibitive, yet users demanded that at least the latest versions of each file be accessible within a matter of minutes through GIS software. So Pierce County used a combination of a 7TB disk-based unit, the TotalStorage DS4500 storage server from IBM Corp., along with the IBM TotalStorage Ultrium Scalable Tape Library.
With this approach, older copies of a file are backed to tape, while newer copies—those still accessed—remain on disk, according to William Morman, an information technology specialist for the county.
“Many customers are taking a blended approach,” said Peter McCaffrey, program director of TotalStorage marketing for IBM’s Systems and Technology Group. “They may use a disk-to-disk backup environment, where they do an image copy of data from primary disk storage. They may do that nightly, but then they will do a consolidated backup to tape.”
“For the number of copies we need to keep and how often they need to be accessed, tape is still the best way to go,” Morman said.
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