No option to shrink partition in Disk Management

AddRAM · 21 Jul 2021

Just boot from your installer and tell it where to install Windows.

alexncfc · 22 Jul 2021

Thanks for all the very helpful advice.

I've now got my partition config sorted by using that really helpful Minitool Partition Wizard program:

256GB C (my current Windows 10 install)
100GB D (where I intend to install Insider Builds)
The rest, H, my data partition

I have a further question though. I've installed another copy of Windows 10 on the D partition and when I boot into that, D is then C, and C is D. Is this normal behaviour? When I boot into my main Windows 10 from Drive C, it shows that on C and the 100GB partition D.

SIW2 · 22 Jul 2021

Apparently it is due to historical reasons, MS decided to use letters A and B for floppies.
The next available letter, C is the default osletter if using windows setup.exe from booted media.
It doesnt have to be, I currently have win11 using Z as the os letter.

No option to shrink partition in Disk Management-win11-z.jpg

If you wanted to choose your own os letter, it should be done after applying the image and before entering the setup routine.
It is not practical to change it afterwards.

NavyLCDR · 22 Jul 2021

alexncfc said:

I have a further question though. I've installed another copy of Windows 10 on the D partition and when I boot into that, D is then C, and C is D. Is this normal behaviour? When I boot into my main Windows 10 from Drive C, it shows that on C and the 100GB partition D.

Completely normal. Usually the OS that is running will assign itself C: drive.

AddRAM · 23 Jul 2021

Whichever Operating System you boot into will be C, totally normal.