Cleanup and file-system repair

Low free space and file-system errors require different responses from fragmentation. Use the relevant tool, then return to Defrag for a fresh analysis.

Cleanup

Open O&O SystemCleaner from Tools. For the integrated cleanup controls in the Classic UI, see O&O DiskCleaner.

1. Open the cleanup application.
2. Select the drives or cleanup areas it offers.
3. Analyze or scan first.
4. Review the categories, file counts, sizes, and descriptions.
5. Select only data you intend to remove.
6. Confirm cleanup in that application's dialog.
7. Return to Defrag and analyze the drive again.

Cleanup can delete data. Read category descriptions carefully, particularly for the Recycle Bin, downloads, previous Windows installations, and caches that another application might need. Deleting a previous Windows installation can remove rollback options.

A scan's size estimate is not a promise that every listed byte can be removed. Some files may be locked or no longer present when cleanup runs.

Check and repair

1. Open O&O Check&Repair from Tools.
2. Select the affected volume and read its reported state.
3. Run the offered check.
4. Review the result before choosing a repair.
5. Follow any restart or exclusive-access requirement.
6. After successful repair, return to Defrag and analyze again.

Checking examines file-system consistency. Repair changes the file system and may need exclusive access. Keep a current backup and use the tool's own instructions for the reported problem.

A setting to check drives before defragmentation and abort upon error does not mean Defrag silently repairs every error. If the check fails, address the failure before retrying optimization.

Hardware warnings

If the drive disappears, produces repeated read errors, or reports poor hardware health, protect the data and investigate the device. File-system repair and defragmentation do not repair physical media. See Drive health.