By Rick Cook
In serverless, or "LAN-free" backup, the data is transferred directly from the disk systems to tape with minimal-to-no interaction with a server. This is done using a copy function built into the SAN hardware. The demands of SAN operation are such that SAN controllers typically have the processing power and intelligence to handle such a function at effectively no increase in cost.
The result should be faster backups that put less demand on system resources.
However "less demand" isn't the same thing as "no demand". While LAN-free backup may not tax servers or LANs, it still requires storage system resources and the use of the SAN channels. The Gartner Group pointed this out in a recent research note discussing the concept, which it called 'outboard backup.'
"Like any backup process, outboard backup will generate intense I/O activity that can saturate disk devices, disk subsystems and channel connections," the note warns. "Application performance will be affected when application I/O is in competition with an outboard backup process."
Another difficulty, the report notes, is the need for standards for serverless backup so that the hardware, storage and infrastructure components can interoperate.
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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.
This was first published in October 2000