Sun's StorEdge Traffic Manager provides high-reliability failover services and improved management for SANs running a variety of modern operating systems, including Windows 2000 and NT. One of the features offered is auto fail back, which automatically restores the system when the failed component is replaced. However Sun recommends that if you are using Version 2.1.1 of Traffic Manager on a system with multiple hosts that you disable the auto fail back feature.
The reason is that with multiple hosts, the auto fail back feature can produce what Sun calls a 'ping pong storm' that can cause all hosts to lose both paths to the storage in the event of a single failure as the system attempts to fail back.
Sun's recommended fix is to disable Sun StorEdge Traffic Manager's auto fail back feature in multi-host environments.
Sun discusses this situation briefly in an application note at:
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http://www.sun.com/storage/san/tm_readme.pdf.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 April 2003