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It's not easy to switch a D drive to a C drive without a complete reinstall. Changing the size of partitions is a better method.

I am using an 2004 Sony VAIO system running Windows XP. I have partitioned the hard drive with 16GB in C: and 60GB in D:. I am getting messages regarding no space left on C:. Can I transfer everything to D: and use that as my main drive as my operating system and use C: for my data files?

In this excerpt from Answercast #36, I look at problems involved in trying to move the boot drive to another partition and suggest an easier path.

Move operating system

The short answer to your question is no, you cannot do that.

Certainly not easily. It would really require reinstalling Windows from scratch to make that happened.

System references to C:

  • The references to drive C, as the operating system drive, are embedded quite deeply into the system when you install it.

Remove the partitions

If you were going to reinstall from scratch, I would actually suggest removing both partitions and having a single partition that is both C: and D: combined.

  • In your case, that should end up to be around 76 GB.

Change partition sizes

The alternative that I'm going to suggest is actually slightly different.

You can run out and get the EaseUs partition manager software. I believe it's free (or at least free for a while) and you can use that software to change the boundary between C: and D:.

In other words:

  • If D: has enough space, enough free space on it.

  • You can actually make the C drive bigger and the D drive smaller.

  • Shifting some of that available space to the C drive.

Backup first!

I would, of course, recommend that before you do that you backup completely (everything!) just in case. Messing around with partitions is one of the fastest ways to lose all of your data, should something go wrong.

Not that something will go wrong. It's a good tool. If used properly, it will do the right thing. It's just one of those things that is very scary at a technical level.

I strongly recommend that you do a complete image backup of both C: and D: before you move the partitions.

Analyze disk space

I might also spend a little bit of time at the article, "Where's my disk space going?"

That will have you download a utility (I believe it's called Tree Size) that will show you where all of the space on the drive is being used.

  • You can see if there is something on your C drive that is taking up a lot of space, that is potentially optional.

It would also be worthwhile running CCleaner to clean out temporary files and a few other things.

  • To free up some space on your existing C drive.

Those are lower priority to me. In all honesty, right now 16GB for a C drive is a little bit on the small side, especially if you've installed any software in addition to Windows.

So, I think you're going to end up moving the partition; moving the partition boundary between C: and D: – making C: bigger and D: smaller.

Swapping drive partitions?

The exact question that you're asking is really not a practical solution to this problem. It really does require starting over from scratch.

Article C5602 - July 19, 2012 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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2 Comments
NL_Derek
July 20, 2012 10:54 AM

A quick way to free up some space is to move the paging file to D:.
My Computer > Properties > Advanced > Performance Settings > Advanced > Virtual Memory and select a (system managed) paging file on D:, then set No paging file on C:. Don't forget to use the Set button before clicking OK. You'll need to reboot after changing it.
But for a long-term solution you need to re-partition (I use gparted which is free)

elangovan s
July 25, 2012 12:09 AM

There is also an other Short cut. Uninstall few Larger softwares (May be MS Office if you are using and such things which occupy a lot of space) and re install them in the D Drive. That will free up the space used by Applications that were once installed in C Drive.

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