Changing External Hard Drive Letter

I have a situation that isn't really a major problem, but is slightly annoying, and somewhat puzzling.

I have an external 1TB Iomega USB hard drive on my system. It is set to be Drive Y. Most of the time, everything is fine. But occasionally, after I boot the system, I'll get the pop up on the screen asking me what I want to do with Drive J. And yes, the "new" Drive J is, indeed, really my Iomega external drive. I can go into Disk Management, and reassign the drive letter back to Y, and everything is fine again.

Sometimes, it keeps the Y drive letter for several months at a time. But other times, the system treats it as a new drive and assigns drive letter J to it--in anywhere from a few days to several months after the previous time.

As I said, it doesn't happen often enough to be a problem, but I'm curious as to what causes it. Anyone have any insights into this little puzzle?

fjawodfc said:

Look in your registry under HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices. That's where drive letter assignments are stored. Find \DosDevices\Y: on the left side and note the data value on the right. The next time it happens, check the same registry location but find \DosDevices\J: and see if the data value is the same as before. Also see if there's still an entry for \DosDevices\Y:.

(Option Two)
https://www.sevenforums.com/tutorials...ndows-7-a.html

Thanks. I've exported that registry key to a text file, so that the next time it happens, I can compare the entries as you suggest. I'll let you know what happens, though it may be some time before I get the behavior again.

I'm guessing that there will NOT still be an entry for \DosDevices\Y: only because when I go to Disk Management to change the drive letter, Y is always available as a drive letter. I'm guessing that if there were an entry for it in the key, the drive letter would not be available in Disk Management.

These are just some random thoughts so please forgive me if it sounds weird. Also, my usual disclaimer: I'm not an expert in anything. :)

Instead of leaving the external drive as just (Y: ) what would happen if you renamed it to something else? Like "Data Backup (Y: )".

Drive - Rename

Another thought is perhaps one of your system files got damaged or corrupt in some way. You could try running a System File Checker scan. It will check the integrity of all protected Windows 7 system files and replace incorrect, corrupted, changed, or damaged versions with the correct versions if possible.

SFC /SCANNOW Command - System File Checker

And a final thought is if you have any other removable USB devices like a flash drive, camera, scanner, etc. If the Iomega external drive is unplugged (or if it has a separate power switch that gets turned off) and another device is plugged in, it might be assigned Drive Y: because that's a known assigned drive letter that's been previously used. Then when you plug in or turn on the Iomega it may get assigned J: because for whatever the reason, it's also a known drive letter that's been previously used. (I don't think Windows 7 or the computer will make a distinction between a HD, Flash drive, camera, etc. But I could be wrong.)

Anyway, just my two cents worth.

Thats the way windows will work. But you can try USBDLM.

USB Drive Letter Manager - USBDLM

Britton30 said:

RP I think you've stumbled on one of Windows 7's annoying quirks. It will assign drive letters as it darn well pleases at times. So far no one has a solution for it but really causes no harm.

Thanks. I agree it's a minor annoyance. But I feel better finding out that it is something that others experience too, and not some more serious problem with my system.

marsmimar said:

These are just some random thoughts so please forgive me if it sounds weird. Also, my usual disclaimer: I'm not an expert in anything. :)

Instead of leaving the external drive as just (Y: ) what would happen if you renamed it to something else? Like "Data Backup (Y: )".

Drive - Rename

Another thought is perhaps one of your system files got damaged or corrupt in some way. You could try running a System File Checker scan. It will check the integrity of all protected Windows 7 system files and replace incorrect, corrupted, changed, or damaged versions with the correct versions if possible.

SFC /SCANNOW Command - System File Checker

And a final thought is if you have any other removable USB devices like a flash drive, camera, scanner, etc. If the Iomega external drive is unplugged (or if it has a separate power switch that gets turned off) and another device is plugged in, it might be assigned Drive Y: because that's a known assigned drive letter that's been previously used. Then when you plug in or turn on the Iomega it may get assigned J: because for whatever the reason, it's also a known drive letter that's been previously used. (I don't think Windows 7 or the computer will make a distinction between a HD, Flash drive, camera, etc. But I could be wrong.)

Anyway, just my two cents worth.

Thanks for the comments. Actually, it has a name (IOMEGA_HDD) which I assume is the default that Iomega gave it. And I have run the SFC and it comes up clean. The only other USB device I have is a card reader (which registers as 4 drives when connected). But I only connect it when I want to use it. Windows always assigns it drive letters J, K, L, and M. And that's fine with me. I originally put the Iomega drive to Y so that if I used other devices, the drive letter wouldn't be affected, since I use it for backup, and my backup software is configured to backup to predetermined drives and folders. But apparently, it is a quirk of Windows, so I'll just live with it.

Bill2 said:

Thats the way windows will work. But you can try USBDLM.

USB Drive Letter Manager - USBDLM

Thanks. Now that I know it is just a quirk, I can just live with it. But thanks for the info on USBDLM.