To use NTFS compression on an entire drive, follow these steps:
1. Make sure that you’re using an Administrator Account.
2. Choose Start > Computer and right-click the drive you want to compress. Choose Properties and then click the General tab.
3. Select the Compress This Drive to Save Disk Space check box. Then click the OK button.
Windows asks you to confirm that you want to compress the entire drive. Windows takes some time to compress the drive in some cases, the estimated time is measured in days.
To use NTFS compression on a folder or single file, follow these steps:
1. Make sure that you’re using a full-fledged administrator account.
2. Navigate to the folder or tile you want to compress (for example, choose Start > Documents or Start > Computer). Right-click the file or folder you want to compress.
Choose Properties and click the Advanced button on the General tab.
The Advanced Properties dialog box appears.
3. Select the Compress Contents to Save Disk Space check box, and then click the OK button.
To uncompress a file or folder, reopen the Advanced Properties dialog box (right-click the file or folder, choose Properties, and then click the Advanced button) and deselect the Compress Contents to Save Disk Space check box.
Remember that if you try to compress the drive that contains your Windows folder, you can’t compress the files that are in use by Windows.
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Gary - InternetFixes Support.