My tip in last week's Windows Client UPDATE, "When Systems Boot Unexpectedly from Storage Devices," described how one of my computers was attempting to boot from a USB device. That story generated reader questions about what kind of device I was using, why I use USB storage devices, and how the OS handles these devices.
A Windows XP computer equipped with USB 2.0 is a versatile machine. The options for connecting to the USB 2.0 ports are varied; I use USB connections primarily for some permutation of storage, although I also use or have used everything from USB-connected 802.11x and Bluetooth devices to scanners and printers. In this column, I want to discuss storage devices and try to explain the somewhat confusing way that XP displays information about these physical devices.
To test how XP displays this information, I attached two Belkin USB 2.0 drive enclosures, each with a Western Digital 120GB hard disk, directly to two of the four USB ports on the back of my Intel white-box computer. I also attached a Belkin 4-port USB 2.0 hub, and to that hub I attached an Iomega HipZip Digital Audio Player with a 40MB PocketZip (formerly marketed as Clik!) disk and an SIIG CompactFlash Card Reader with a Lexar Media 32MB USB-ready Compact Flash (CF) card. The computer already has a SCSI controller with the boot drive, a Promise Technology Ultra100-TX ATA controller card, and two 60GB hard disks.
Where do you look for information about these storage devices? The first place is the system tray. Clicking the Safely Remove Hardware icon brings up the window that lets you stop and start removable hardware. In the default display, all I see are four entries labeled USB Mass Storage Device. Obviously, this display isn't very useful if I want to use this control to stop a device before I remove it. Fortunately, selecting the "Display device components" check box brings up a dialog box that shows enough information to identify each attached device; however, I still need to know what I have installed before I can make sense of this information. Right-clicking the device information in this dialog box displays device properties that provide detailed information about each device. However, my CF card displays as a generic hard disk, so no further information for it is available.
The next place to look for information about attached devices is in Device Manager. Now the situation gets really confusing: Where do you look for information? Under the USB Serial Bus controller entry on my machine, 13 separate subentries are listed: 1 Generic USB Hub entry, 4 entries identifying the host controller, 4 USB mass storage device entries, and 4 USB Root Hub entries.
When I check under the Storage Volumes entry, I find two subentries: One identifies the Iomega music player, and the other identifies a generic volume on a generic device, which I know from the process of elimination is the CF card. I still don't have a lot of information.
Next, I look under the Disk Drives entry and become further confused because the entry shows a lot of SCSI drives, and I know I have only one. But I also know that the drives attached to the ATA controller card will be shown as SCSI attached, so I don't get sidetracked.
I still haven't found detailed information about any of my storage devices, nor have I discovered where the information could be hidden. Well, it turns out to be hidden in plain sight, sort of. When I added the removable media devices, they turned up in the Disk Management application. The Iomega player displays with a volume name of PocketZip40, which clearly states what the device is, and the CF card displays with a volume name of Lexar Media, Disks 5 and 6, respectively, and the device is tagged as removable. Curiously, the hard disks in the enclosures show up as normal disks and aren't marked as removable.
My research shows that there is no single location that can report comprehensively about devices I attach to the USB bus. This shortcoming is bound to present a diagnostic problem as more and more users make use of the USB interface's flexibility.