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. It guides you through Analyze, Clean up, and Finish.
2. Clear the categories you want to keep. Each row says what it holds and what removing it means.
3. Choose the drive scope at the bottom, then Analyze. The analysis deletes nothing.
4. Review the categories, file counts, and sizes it reports.
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.

The numbered steps at the top show where you are in the process. Every category is selected by default, so read the descriptions before analyzing: some of them, such as the browser cache or the Windows Update cache, hold data that Windows or your applications will have to fetch 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 CheckAndRepair from Tools using the Check & repair card.
2. On the Check step, select the areas to examine and clear the ones you want to skip.
3. Choose Check and wait for the result. Depending on the amount of data and the type of disk, this can take several minutes.
4. Review the result on the Repair step before letting the application repair anything.
5. Follow any restart or exclusive-access requirement.
6. On Finish, read the summary, then return to Defrag and analyze again.

The application works in three steps: Check, Repair, and Finish. The check covers the component store, the system files, the disk, and the Windows recovery environment; each entry explains what that area is responsible for.

Checking examines consistency. Repair changes the 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.