Getting bombarded with errors that the backup-to-disk folders are OFFLINE?? Recently upgraded to BE 2010 and started fresh with new backup jobs. Running Server 2008 R2 x64 on an HP DL360 G4 and have a PCI USB 2.0 installed with 3 2TB USB drives attached. These drives are where the Backup-to-disk folders are located and have run successful backup jobs with no issues. Why is this happening, didn't happen prior to the upgrade running 12.5?
If you remove the USB drives, you have make sure they are online when you plug them in again.
If you are not using BE 2010 R2, then you should upgrade to this version. There are a lot of improvement in the handling of USB drives in BE 2010 R2.