My C Drive is filling up, can you help?

By | 31 October, 2008

I was asked today if there is anything you can do if the C: drive of your Windows computer is filling up. In some situations there is. The two main bits of advice I could offer were (1) Reducing the amount of space System restore takes and (2) Moving your pagefile.sys.

(1) Reducing System Restore Disk Space

Windows by default saves 10% (15% in Vista) of all disk space for System Restore points. By reducing the amount of space, you reduce the number of valid System Restore points. In my experience you only really use the last two or three System Restore points, anything more and you’d start thinking of a rebuild of your PC as something must be seriously wrong, and rolling back further might cause other issues.

So how do I do it?

Here’s a video of how it can be done (for XP)…. Any changes made to your computer are at your own risk, I’ve done this many times on my PCs but can not guarantee the process may work on yours.

So what did we do here?

  1. Start > My Computer, Right Click on the My Computer Icon.
  2. Go to Properties on the Context Sensitive Menu
  3. There are a load of tabs in this Properties dialog, go to the tab that says System Restore
  4. There is a slider on this page, adjust it to a level at which you’re happy, I usually choose around 3% which on todays larger hard disks should be more than enough.
  5. Click Apply and OK.


(2) Moving your Pagefile.

Let’s start at the beginning. What’s a Pagefile?

Computers have physical RAM (that’s Random Access Memory) which an Operating System uses to function. When the physical RAM is exhausted, Windows starts putting the information on to disk instead of in RAM. Disk is slower than RAM so you can often see the computer starting to slow down and become unresponsive when it starts swapping memory between RAM and Disk.

The typical guideline is that the amount of disk allocated to this process (called pagefile.sys) can be anywhere between the amount of physical RAM installed and double that.

If we want to move the page file, first we have to have somewhere to move it to. If you’ve got more than one physical disk in your computer, or multiple partitions on one disk you’ll be ok. If you have just a C: drive, then you can’t go through this process. Also I wouldn’t move the pagefile.sys to a USB drive, you might one day unplug it and Windows might just go into a loop of not being able to boot up. Not good.

So we’ve got the pre-requisites. Space on a physical partition that isn’t the C: drive. How do we do move it then I hear you ask?


  1. Start > My Computer and Right Click Properties
  2. Go to the advanced tab
  3. Click the settings button in the performance section of that tab
  4. In the performance options tab, click advanced
  5. Click the change button on the virtual memory section
  6. First set the new Pagefile, using the same space settings as the old one, click set once done
  7. Then delete the original one, by selecting the C: drive and click no pagefile and click set
  8. Computer will want to reboot. Click ok when ready. Done

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