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You’ve cleared out enough space on your hard drive. You’ve got the Windows install disc ready to go. When you try to use Boot Camp to create a Windows partition, you come across the following error: “The disk cannot be partitioned because some files could not be moved.” The suggested solution of reformatting the disk and restoring the data will work, but is quite a hassle. Surely there is an easier solution? Well, there is.

The Problem

Before getting into the solution, we must first understand the cause of this problem. Boot Camp tries to create the Windows partition by allocating it a contiguous area at the end of the disk. To do this, it tries to move all of the files currently residing there onto another part of the drive. However, it has a problem moving large files (larger than several hundred megabytes in size) and will time out before succeeding, returning the above error. The most common files causing this problem are large video files.

The Solution

The solution then, is to move these large files residing at the end of the disk using another method. There are a few different ways to do this.

• Manually: If you have another hard drive (external or networked computer, for example), you could move the large files off temporarily. Of course, this would require some knowledge of which files are the culprit. You can use a utility such as Disk Inventory X to determine the largest files on the drive and move those off. This is how I solved the problem.
• Defrag: You could also use a defrag utility to move the files towards the front of the drive. I do not know of any free programs that would do this, though a paid one that would work is iDefrag ($34.95). You would have to do the full defrag, which requires rebooting. Even if you don’t pay for it, the demo is useful for showing you a mapping of where files reside on your drive, giving you an indication of how much you have to move. The demo version will not do the full defrag necessary to move the files to the front, however.

Once the large files are moved away, Boot Camp should have no problem moving the smaller files itself. Now you can continue with the Windows install to make your Mac much more versatile.