Dual boot system- installed on separate drives- Booting shows diff Drive Letters

Dear Friends: on
I have operating systems W 10 ( upgraded from W7 with a lot of garbage on it) on F: drive and Win 10 which I clean installed on C: drive ( nothing on it) after removing/formatting vista . These are 2 two separate drives ( not partition) on my PC.

Case : When I reboot the PC, it gives me a choice to select Win 10C ( clean installed one) or Win 10 (upgrade) which I call Win 7U to avoid confusion.

When I select Win 10 ( Boot Drive C), W 7U is showing up in D drive ( I can open the the D drive and see all files). However, when I choose Win 7U ( Boot drive F), W 7U is showing up in F drive ( I can see all the files).

At this time I have no problem, running these OSes. But these Drive letters are confusing me.Is it normal.

Can I hide the D rive ?


Knows where his towel is.
Staff member
Disk letters are not "real".
When your PC is turned off, none of the partitions have letters at all.
Letters are virtual labels given to a partition (or device) by the running version of Windows. i.e. they are merely entries in its registry.
Since each OS has an entirely independent registry, it follows that each OS will have its own completely independent map of device/partition letters.
It is somewhat under your control, as the method you use to install an OS will influence what the installed system calls itself (generally C, but not under all circumstances).
Once a system is installed, what it calls itself is fixed in stone, but what it calls everything else is under your control using the Disk Management snap-in.
The only exceptions are partitions flagged as "system" "boot" or "page"
When you boot each OS where do these flags reside ?

Disk Management flags have the following meanings

"boot" = "this is the system you're running"
"system" = "this is where I found the boot files for the currently running system"
"active" (on the first HDD in the BIOS boot sequence) = "this is where I started the search for the boot files"
"active" (on subsequent HDDs in the BIOS boot sequence) ="this is where I will look if I don't find something in the MBR on the first HDD"