Drive letter assignment to hot-swap drives being forgotten

Hi, I can only confirm that assigning a drive letter to a USB drive via Disk Management (R in my case) works for me- that's my MAcrium Reflect image storage drive so it's always assigned the same letter - late in the alphabet.

Hopefully someone here has experience with hot-swap drives and caddies.

djeyewater said:

My USB stick is fine, that always gets assigned the same letter. But not my hotswap drives. It could be something to do with having two different drives mapped to the same letter.

That "could" be an issue.

That said, not sure what's going on but when you assign a drive letter to a particular drive, it "should" be remembered, and still usable unless there's currently in-use another drive using the same letter. In that case the later drive is reassigned the first available drive letter.

Example: I just replaced a 1TB HDD hot-swappable drive with a 1TB SSD drive. The old HDD drive was assigned drive letter "I", but when I moved to the SSD drive, I changed it's drive letter to "I", and now when I plug in the old HDD drive it's letter has changed to "J" because I is already assigned. That even if I removed the SSD drive (I), the old HDD drive will still use "J" because that's what Windows has assigned it.

That said, since we're talking hot swappable drives, check your BIOS and under Peripherals, SATA Configuration, there may be an option for hot swap drives, if so, make sure it's enabled. Now when you swap drives and reboot the PC, that drive's letter should be remembered, even if it was removed while the PC rebooted.

Let me know if this helps.

djeyewater said:

I have two SATA hot-swap drives that I alternate between each day for backups. When using Windows 7 I was able to assign the disks to g: and then after the initial assignment, windows would remember this and assign it to g: on each subsequent use.

But with Windows 10 it seems to forget the assignment after a reboot, and assigns d: (the first free letter) instead. (Quite possibly this isn't actually related to a difference between Win 7 / 10 though - when using Win 7 I had a drives on d:, e:, f:, and so g: was the first available letter. On Win 10 I no longer have the d: and f: drives attached, and so d: is now the first available letter.)

To be clear:

• The hot swap disks are not permanently attached
• Only one hot swap disk is ever attached at a time
• Both hot swap disks have been assigned to g: (but this isn't sticking)

Anyone have any ideas?

You could create a batch file with diskpart that remove the drive letter and reassigns the one you want.
The drive number n should be last on list.

Initially


diskpart
list disk (to identify disk number)

Batch file e.g. letter.bat contains one line

diskpart /s letter.txt

and letter.txt contains

select disk n (n from above)
remove
assign letter= J (or whatever you want)
exit

and each time you swap drive, just run letter.bat.

djeyewater said:

Thanks for the replies. So far as I can tell, it seems like probably when setting a drive letter, windows stores the unique identifier of that drive as being mapped to that drive letter. Then when doing the same with another drive, the new mapping overwrites the previously set mapping, rather than adding it as an additional mapping. So when you then switch back to the first drive, that mapping has been lost.

Something like that.

The easiest thing for me is simply to change my backups to go to the d:. Since that's the first free drive letter, that's what will always be assigned to the drives when I plug them in.

I'm not sure that's the best approach for hot swap drives, but...

That said, I gave you a BIOS suggestion but you seemed to have dismissed it?

Regardless, when one asks for help, and another replies with a suggestion, it would be nice to know if you seen it or not. Thanks

My reply in red.

I'm in a busy class so I might have missed it, did somebody already mention that for any external device to keep an assigned drive letter must be plugged into the same usb hub's port or the same laptop's usb port every time.