Several companies, notably Silicon Graphics Inc. and Sun have demonstrated hot backups at about a terabyte per hour. While the configurations these demonstrations used are not common and definitely not cheap, all the components are off-the-shelf and the basic architecture is widely applicable to enterprises needing high-speed backups.
The key to backups in the terabyte-per-hour range is high performance hardware with parallel data streams managed by high performance software such as NetBackUp from Veritas Software Corp., Alexandria from Computer Associates or Legato NetWorker. In the case of the Sun demonstration, the hardware included a Sun Enterprise 6000 server with 12 250-MHz CPUs and a total of 2 gigabytes of RAM. Storage was 17 SPARCStorage arrays with over a terabyte of total capacity and backup was to 24 StorageTek RedWood SD-3 tape drives. The connection between the two was 24 S-bus based Differential Wide SCSI channels. Backup software was Sun's version of Veritas NetBackUp. SGI used an Origin 2000 server with 16 195-MHZ CPUs and 5 GB of RAM. The system was equipped with 24 XIO slots and 20 UltraSCSI cards providing a total of 80 SCSI channels feeding 38 IBM 3590 tape drives from 26 Origin Vault arrays. The backup software was Alexandria for one series of tests and SGI's version of NetWorker for another.
In both cases the test files were large databases created with Oracle Corp.'s DBMS. Oracle includes Enterprise Backup Utility, which creates parallel data streams to feed the backup system while maintaining a consistent snapshot of the database.
The results were impressive. Sun delivered 941 gigabytes per hour of sustained throughput in an on-line backup. SGI reported just over a terabyte per hour in an on-line backup using NetWorker and 985 gigabytes per hour using Alexandria. The tests were not strictly comparable, although the conditions of the SGI test were probably more stringent than those of the Sun test.
White papers describing the Sun and SGI demonstrations are available at the firms' respective web sites. Sun's is at: http://www.sun.com/storage/white-papers/hspeedbackup.html, and SGI's is at: www.sgi.com/origin/2000/terabyte.html.
About the author: Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.
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