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Flash memory drives are not given a drive letter in Windows Explorer (Microsoft® Windows® XP)
Published Date : 16 Feb 2006   Last Updated : 05 Mar 2010   Content Ref: TEC591242  





Symptoms

You may have a Microsoft® Windows® XP system which does not appear to work correctly when you insert a flash drive memory stick. Symptoms include:

  • Some flash drives work and you see a drive letter in Windows Explorer, but other drives are not assigned a drive letter.
  • The Safely Remove Hardware icon in the System Tray is present even when a flash drive is not given a drive letter (though no drive is listed).
  • No flash drives are assigned a drive letter but the Safely Remove Hardware icon is visible in the system tray when a flash drive is connected.

In some cases you may find that, for instance, an RM MiniSafe flash memory stick is not given a drive letter by Windows®, but another type of memory stick is.



Cause

Drive letter assignment

When a USB storage device is connected to a Windows® XP system, Windows® will install the device dynamically using generic USB mass storage device drivers. Once a drive volume is installed, the file system will attempt to mount the device and assign it a drive letter. If the device had previously been given a drive letter, it will be assigned the same drive letter again (if available). If the USB device has not been seen before, it will be assigned a new local drive letter which will be the first one above the last local drive letter starting from A: or C: (if available).

This drive letter assignment can fail under the following conditions:

  • The user has insufficient access rights to mount a drive volume.
  • The number of available drive letters has been restricted (eg, by a Group Policy)
  • You have already connected one or more USB storage devices (eg, digital camera, USB CD drive, etc.) and have some network drives mapped.
  • No local drive letters are available (eg, you have local drives C:, D:, E: and F: and network drives mapped to G:).
  • The flash memory device was previously mounted as a drive letter which is now no longer available.

A typical scenario in the last case is that you had previously inserted an RM MiniSafe flash memory drive into a new system and it was assigned a drive letter by Windows® (eg, H:). Later you have connected the PC to a Domain or run a script which has mapped some network drives to various specific volume letters including H:. Now when you insert the RM MiniSafe, the MiniSafe cannot be assigned to H: because this is already taken by a network drive mapping. Microsoft® Windows® will not use a lower letter (eg, G:) even if it is available because it remembers that this drive was previously mapped to H:. Mapping it to a different letter could cause the user bad-path issues with pre-installed applications and shortcuts which already point to the H: volume. Microsoft® Windows® will not use a higher drive letter because it will not automatically map a local drive above a network drive.

Example Scenario:

Initial Drive assignment
A: Floppy
B: free
C: Hard Disk
D: Hard Disk
E: Hard Disk
F: CD-ROM
G: USB-DVD
H: RM MiniSafe

Drive assignment after reboot and mapping network drives
A: Floppy
B: free
C: Hard Disk
D: Hard Disk
E: Hard Disk
F: CD-ROM
G:
H: Network Drive mapped
I: Network Drive mapped
etc.

If the same RM MiniSafe is inserted, it will not be assigned a drive letter at all. However, if a different USB drive is inserted, it will be mounted as G:.

Note: Re-formatting the RM MiniSafe may appear to fix this issue because Microsoft® Windows® will not recognise the new Volume Serial number given to the drive by the reformat process and so Microsoft® Windows® will not remember the previous drive assignment.



Procedure

Even though no drive letter has been assigned in Windows Explorer, you can manually change or assign a new drive letter as follows:

Note: You must have Administrator access privileges to the system.

  1. From the Start menu, choose Settings, Control Panel, Administrative Tools, Computer Management.
  2. Click the Storage item in the right-hand panel.
  3. Click the Disk Management item.
  4. Right-click the storage volume that you wish to assign a drive letter to from within the lower right-hand window pane.
  5. Click Change Drive Letter and Paths....
  6. Use the Add, Change or Remove buttons as appropriate.
  7. Click OK to save the settings.


Checks

If you cannot see your device in Storage Manager, then this indicates a driver issue. Check for the correct detection of the USB device in Control Panel, System, Device Manager.


Possible Issues

Because Windows® remembers drive letter assignments for each device, you may find that you will have to repeat the procedure above for any device that you may have previously connected before extra network drives were mapped on your system.


More Information

Microsoft® have this issue documented:

http://support.microsoft.com/default.aspx?scid=kb;en-us;297694

http://support.microsoft.com/kb/925196



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Document Keywords: stick, vtec, minisafe, netac, vdrive, drive, dongle, letter, icon, explorer, hard disk, floppy drive, file manager, map, share, mount, volume, partition


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