How to Compress the Entire Hard Drive in Windows
Windows offers a single command that sifts through every file on a hard drive and applies the compression attribute to them. The result is that the entire hard drive is compressed and takes up less space. This strategy isn’t a surefire solution to a cramped hard drive, but it can be done and may buy you a little time. The process can take several hours. Plan accordingly.
To compress an entire hard drive, follow these steps:
Open the Computer window.
In Windows XP, open the My Computer window.
Right-click a drive icon and choose Properties from the shortcut menu.
Place a check mark by the item Compress This Drive to Save Disk Space.
Click the Apply button.
Ensure that the second option is selected in the Confirm Attribute Changes dialog box: Apply Changes to Drive X:, Subfolders and Files.
If prompted with a UAC, click the Continue button and then type the administrator’s password or click Continue (again) to continue (again).
If during this process, you encounter file errors, click the Ignore All button. Files get busy and are in use by other processes, for example. There’s no way to compress them all.
It takes a long time to assign the compression attribute to all files on the hard drive.
If you grow weary, you can always click the Cancel button and resume later.
Close the drive’s Properties window.
No confirmation dialog box appears when the operation is over, which is kind of a letdown.
To confirm that the files on the drive have been compressed, open the drive icon and view the files; you discover that the files are compressed and sport blue filenames. You also note that some folders are compressed and others are left alone. That’s okay: The compression being used by Windows doesn’t compress everything well.
The kicker, however, is to discover whether any disk storage savings have resulted. To view this information, open the drive’s Properties dialog box and take a look.
This file compression works on the fly. Windows decompresses files when you access them, and then it recompresses those files when you save them back to disk.
Even though Windows may compress a file, it doesn’t necessarily mean that the file will occupy less disk space. That’s because not all files compress well.
To decompress the drive, repeat the preceding steps but remove the check mark in Step 3.