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[previous article] [next article]The Engineering Computer Network provides nightly disk backups as one of its core services. The disk backup system has evolved over the years to keep pace with the growing number of systems and disks the ECN maintains.
Until 1988, mass storage systems within the ECN were backed up to 9 track reel-to-reel tape units. These units were connected to PDP, VAX, and Gould mini-computers. Each of Engineering's seven primary machine rooms had one or more tape units, each costing approximately $45,000.
In 1988, the ECN staff beta tested one of the first 8mm helical scan digital tape units known as Exabyte tape drives. After working out many bugs in this new technology, the Exabyte tape drive became the standard backup device across the ECN. Today, the ECN operates 68 Exabyte tape drives which backup approximately 1 terabyte of data on 83 primary file servers and workstations. The backup model was to attach tape drives to primary file servers which served disk space to workstations over the network via Network File System (NFS).
This backup model began to fail the ECN in the mid 1990's for several reasons. First, both the number and size of disk drives on ECN systems increased due to decreases in price and increases in capacity. The surge in disk capacity across the network overwhelmed the relatively slow transfer rate and low density of the Exabyte drives. Second, newly purchased computer systems were being delivered with disk drives capable of storing the entire UNIX operating system, with free space to spare. Our customers realized the I/O performance gain associated with using local disk space as opposed to disk space served by NFS. The model of attaching a tape drive directly to a system for backups does not scale well to hundreds of desktop workstations with local user file systems. Last, the current model is not capable of providing backups of desktop PC operating systems such as Windows 95 and Windows NT.
The ECN staff began evaluating backup software and tape library systems in the summer of 1996. In late 1996, Hewlett Packard's Omniback package was selected for pilot evaluation. The pilot involved using Omniback to backup more than 75 servers, workstations, and desktop PCs to 4 Exabyte tape "stackers" located on an ATM network. The pilot project was a success. In the summer of 1997, ECN purchased a StorageTek 9710 robotic tape library system and the server hardware required to run the Omniback system and drive the library from the ATM network backbone. The 9710 tape library is a robotic system currently configured with 4 Quantum DLT-7000 tape drives and over 28 terabytes of storage capacity.
The ECN will begin moving the Omniback system into full production this fall. The current pilot systems will be moved to the new hardware first. Systems still using the old backup model will then be migrated to the new backup system.
The ECN is confident the new and improved services and capacity of the Omniback system will serve the Schools of Engineering for many years to come. For questions concerning ECN backup services, please contact your Site Specialist, Dave Carmichael ( carmicha@ecn ), or Bill Simmons ( simmons@ecn ).
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