Windows 10: Booting Windows 10 from D drive

Currently, I have Windows installed on my C: drive (HDD). If I install it on my D: drive (SSD) aswell, and then format the C drive, will the current C drive (HDD) still be the C drive, or will the D drive (SSD) become the C?
Sorry for poor explaining and confusing question.

PS: I want the HDD as my C: drive

:)

 

Changing the default hard drive

An alternative method is to extend C drive with free space in D drive, which does not need a clone or reinstall. Unfortunately, Windows built-in disk manager does not allow you to merge two partitions or allocate free space from existing partition to system
drive. Turn to third-party software.

Here is a tutorial on
how to transfer space from D drive to C without formatting in Windows 10. Hope it is helpful.

By the way, I agree with Fred. You can clone system drive to D drive or do a clean install on D drive. It is not common that system drive has only 600 MB in size. Except for changing boot priority in BIOS after cloning, you can also delete old system drive
C on the hard drive after the system successfully boot from D drive.

 

Windows 10

I have reinstalled Windows 10 recently but all my system files appear to be going to the c: drive which is much smaller than the D: drive and as a consequence is rapidly filling up. Do I need to reinstall to allow system files to boot from the D drive?

 

First, when you install Windows to the SSD make sure and have the HDD disconnected. If you don't, your system partition and boot files will stay on your HDD and when you format it, you will erase them and have to fix Windows booting which can get quite involved.

Whatever drive Windows boots from will be C: drive and the other will be D: drive. When Windows boots from the SSD, it will be C: drive.

You can establish somewhat of a permanent file structure by using directory junctions. Google Windows directory junctions and the mklink command.

 

It is possible to force Windows to install on a different disk or partition whose label is other than C - people have discussed this on earlier editions of Windows. Don't know whether there's a specific issue with Win 10.

However, you want to keep all the partitions associated with your Win 10 installation on the same physical disk (there will be more than one).

But- it's so unusual to attempt this, doing so is bound to cause you problems at some point, and I cannot recommend it.

For interest only (and I'm not going to suggest this is either correct, good practice, the only way, or something to attempt):

 

HDD and SSDs do not have a letter hard written in it, it's assigned by OS and it's common that OS assigns BOOT/OS drive /partition letter C:. Other drives are assigned a letter in the order set in BIOS.
One example.
2 HDDs, one with W7 and one with W10. If you boot from drive with W7, that one would be C: and other one D:.
Same computer, BOOT from drive with W10 and it will become C: and drive with W7 drive D:.
If left to default settings, same thing would happen even with one drive divided/partitioned to 2. Other partitions OS may make will be left without any letter and so invisible to Explorer but can be seen in Disk management.