I've been using external hard drives to backup my server for the past 6 months and recently the external USB hard drives stopped working (not recognized).
The event log reports Event ID 219 (Source: Kernel-PnP) when connecting the drive.
The device manager reports an issue with the "USB Attached SCSI (UAS) Mass Storage Device"
Device status reports: Windows cannot use this hardware device because it has been prepared for "safe removal", but it has not been removed from the computer. (Code 47) To fix this problem, unplug this device from your computer and then plug it in again.
So far the only resolution has been to restart the server prior to running the backup job. Upon reboot the drive is detected and works fine. It's when I go to swap the drive that I have an issue with the next drive not being recognized. Whether or not I just disconnect the drive or use the Safe Removal function, the next drive will not work until I reboot.
I have attempted to update the driver (USB Attached SCSI (UAS) Mass Storage Device) but Windows Updates indicates it is current.
Driver Date: 6/21/2006
Server: Dell PE T320
OS: Windows Server 2012
I've installed latest bios and chipset drivers from Dell's website.