B2D devices keep going offline, only they're not
We keep having backups fail because the B2D devices are being marked offline. They're not offline, though - I can access them, and nothing in the eventlog suggests they are actually going offline. 2010 seems to just think they are.
If I mark them as online again, then the backups start working, but I can come back a few hours later and find they've failed.
Server 2008 SP2 (x86), BE 2010, 2GB RAM. B2D devices are folders on a variety of external, USB2 connected hard drives.
Have tried replacing the external drives, using different USB ports, etc. Have checked power management in BIOS and Windows - nothing is set to power off at all. External drives not set to spin down on idle either (although even if they were, they shouldn't in this case as they're not idle!).