Solved How do I stop identical WD USB drives showing as the same drive letter

[AussieColin]

I've bought three WD 3Tb Elements external USB 3 drives (they were on special). The problem is that Windows 7 is not seeing them as separate drives. If you plug in one then the next one simply doesn't appear, either in My Computer or in the Disk Management utility.

This has happened to me before (with two identical 2Tb WD Elements drives) but I was able to fix the problem by manually assigning drive letters to each one. Once I did that they were recognized as separate drives. Unfortunately this doesn't seem to be working with these ones.

Specifically:

• I plug in drive #1 and assign it the drive letter S.
• I then unplug it and plug in drive #2. It appears also as drive S (this is what normally happens).
• I manually assign this second disk the drive letter T.
• What SHOULD happen at this point is that when I now plug in the first drive again it will still have drive letter S and the two will both show. Instead only one of them will register at a time and they both now (separately) show as T. Both in My Computer and in Disk Management the second is simply invisible.

Any ideas? How do I make the drive letters 'stick' to their drives as I've been able to with other similar drives in the past?

 

[jumanji]

This happens because all the three drives have the same Unique Id.

Connect all the three drives and go to Windows Disk Management.

Only one drive will get the drive letter and the other two may be offline because of the signature collision.

Right click on the drives with a red arrow pointing down and bring them online.



Plug out the drives and plug in. Now all the drives will get a different drive letter.

EDIT: You may also check and change the Unique ID of the drives using diskpart. http://www.laurentkempe.com/post/Windows-7-Disk-is-offline-because-it-has-a-signature-collision.aspx

 

[AussieColin]

Thank you! Worked perfectly. I hadn't scrolled down far enough in Disk Manager to see that the second drive was appearing, just marked as "offline". Now that I know the extra step I'll be good the next time I run into this.

 

[jumanji]

Glad I could help. This is a common problem when you buy the same brand drives in bulk.

Just for your interest you may see these threads.

http://www.sevenforums.com/hardware...al-drives-one-not-recognised.html#post1758130

http://www.sevenforums.com/hardware...s-assign-same-drive-letter-all-externals.html

The second recent one is of course my baby and reverse engineering.