How TerraServer Protects Millions of Topgrahic Maps, Aerial Photographs
In a recent news release it was announced that The TerraServer project uses a ADIC(R) Scalar(R) 1000 storage networking tape library to provide data protection for one of the Internet's largest and busiest sites.
The TerraServer Website, a joint project of the United States Geological Survey (USGS) and Microsoft, provides public access to one of the world's largest online resources -- more than 300 million images of the United States from aerial photographs and topographic maps. Storing the images, which now cover about 90% of the country, are three SQL Server 2000 databases totaling about 3TB, all maintained with 99.99% availability. With an average 40,000 users and five million hits a day, TerraServer is one the Web's most frequently visited sites.
"We had two purposes for this project," explained Tom Barclay, TerraServer project manager. "First, we wanted to make the USGS images available to the public. Second, we wanted to demonstrate state-of-the-art data access technology that other organizations could use for their own projects -- to prove a true, enterprise-class solution set under severe, unpredictable, and very public conditions."
To support the site's voracious demand for scalability and performance, its managers phased in a sophisticated storage area network (SAN) infrastructure. Disk, server and fabric resources are provided by Compaq. Backup protection is delivered by the ADIC Scalar 1000 storage network tape library and VERITAS NetBackup software.
On the data access side, the SAN consists of a cluster of four servers each running SQL Server 2000 on Windows 2000 Data Center Edition. Each server has two host-bus adapters (HBAs) that connect to two separate Fibre Channel three-switch fabrics for performance and redundancy. The two switched fabrics each connect to a common RAID array with triple-mirrored images of the databases. "The SAN provides us a much more easily managed environment. Access is fast, performance is high, we have full redundancy, and it is easy to add additional storage."
Backup for this environment required a tape library designed with storage networks in mind.
Integrated Storage Network Support
"When we first converted to SAN backup, our legacy equipment had issues with backup and recovery interruptions. Installing the Scalar 1000 LTO library with its storage networking support made a dramatic difference," explains Barclay. The LTO tape technology meant faster performance and fewer tapes, and the Scalar 1000 provides important SAN capabilities not available elsewhere. In addition to automated health checks of connections within the SAN, the system features data-path conditioning, which reduces the chance of backup interruptions and improves drive performance through extra error correction and command queuing. "The bottom line was much better performance and reliability with the Scalar 1000," said Barclay.
Dual Fabric Support and SAN Security
"The Scalar 1000's unique SAN security and dual data-path features were also important for the TerraServer site because they easily support a dual-fabric configuration," added Barclay. Channel zoning capabilities in the library make the SAN management task less complex by limiting the targets which each initiator could see. "Although the library was initially added on a separate fabric (using a third HBA in each server), its multiple port configuration is designed to support separate connections to two fabrics at the same time. The next deployment stage planned will take advantage of this feature, providing separation within the library to match the disk architecture."
The Scalar 1000's SAN Firewall allows different LUNs in the library to be accessed only by specific initiators. This feature provides software-controlled separation of storage resources to maintain redundancy and security within a single library. VERITAS NetBackup provides full support for this virtualization, allowing the different SAN partitions to be treated as logically separate storage elements.
"NetBackup and the Scalar 1000, with its integrated storage network support, bring mission-critical reliability to enterprise SAN backup. Before we put the systems on line, we repeatedly backed up and restored the entire database using different server systems and configurations. It was phenomenally successful. We think our next advance will be a serverless backup implementation where the data will be moved by multi-streaming data-moving agents in the library storage subsystem rather than by the servers."
-- Data Protection Site: SAN backup of 6TB TerraServer Web site
-- Data Protection Solution: Scalar 1000 with four IBM LTO Ultrium drives and 188 cartridge positions (scalable to 48 drives/ 938 cartridges) and VERITAS NetBackup
-- Key Features: Data-path conditioning for increased reliability and performance; dual FC ports and SAN Firewall for dual-fabric support
-- SAN Configuration: Compaq Proliant 8500 Servers with SQL Server 2000; 18TB StorageWorks RAID array