How can I delete C: drive and make D: drive main boot drive?

October 12, 2016 at 03:52:27
Specs: Windows 10
I've partitioned my hard drive due to not being able to load windows 10 over windows vista, so c: has vista and d: has windows 10. It wont let me merge the two together or delete C: saying the computer will be unbootable. Is there a way of making D: the main boot drive and deleting/merging C:?

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October 12, 2016 at 05:52:21
Vista was there first and installed into C: - that being the active Primary. C: will have the boot-loader (assorted startup files for "both" Vista and the later installed Win-10) - and presumably D: is an Extended partition... Or did you make D: as a second Primary - which I suspect is unlikely as very few do, and even fewer realise it can be done - at time of creation.

Why do you wish to merge the two partitions?

In the past - although M$ advised against it - it was possible to have two (even three) flavours of windows in the same partition. Having done it with assorted versions up to and including XP-Pro I know it worked that far.

In your situation you might be able to remove Vista - but retaining the Win-10 boot loader in the process (which is how both OS are now booting). Then (and I haven't played with Win-10 so I don't know how forgiving it is when tweaking partitions...) you could shrink C: and then expand D: into the free space...

To remove Vista - simply boot into Win-10; then navigate to C: drive and delete the Vista folder. Do NOT reformat C: as to do so will render Win-10 unbootable too. Although I doubt you can reformat C: when Win-10 is actively booted via it.

There will be a few other Vista startup files to remove (later); but one would not delete anything related to Win-10.

And of course you may have data files in D: as well; so safeguard those by coping to external storage. DVD at least and/or an external hard drive too is nice(r). Then if anything goes amiss your personal data files (photos, music documents etc.) are safe elsewhere.

There are one or two other possibilities that one could consider; but first - why need to merge the C: and D: ? And what kind of partition is D: ?

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October 12, 2016 at 12:58:31
I assume you wanted to keep programs installed under Vista working under Windows10. That is not possible. Installed programs would need to be re-installed under Windows 10, assuming they are compatible.

Vista came is both 32 bit and 64 bit but the 32 bit is much more common. This is important because many programs written for 32 bit operating systems have 16 bit elements in them and will not run under Windows 10 64 bit version.

You may want to keep both Vista and Windows 10 in order to use programs installed under Vista.

Provide more information for better advice.

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October 12, 2016 at 21:07:20
NOTE: All Windows operating systems consider the partition they are installed on to be C drive when you are actively in that operating system. For this reason, use the partition's sizes and/or relative positions on the drive to do any partition changes. <If you are actively in Windows 10 and you go to Disk Manager and look at the partitions, you will see D drive before C drive and C drive will be listed as active boot drive. Shrinking D drive from there may be possible and will actually shrink the Vista's C drive.> Of course, back up as mentioned above before attempting any changes. This way the worst that happens is you just wipe the whole drive, reinstall and restore your back up, maybe an hour or two at most.
Also note when using multiple OS, it is best to Label the drives yourself so as to reduce he confusion like this and help keep things straight. I even label drives in a single OS like 'Windows 7', 'Storage', 'Back Up', 'Image Drive', etc.

You have to be a little bit crazy to keep you from going insane.

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October 14, 2016 at 02:28:58
It's true that Windows always considers the drive that it boots from as C:, but this does not have to be the Windows System Directory, the drive that the main Windows files are installed on. The environment variables %SystemDrive% and %SystemRoot% should be consulted if the drive and Windows directory need to be located.

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