Thumbnails folder are not removed when they are no longer used.
While it poses no threat in general but theoretically it can cause a horrible and slow death to the file system.
As of Confluence 6.2.4, parent folders will be removed once thumbnails are deleted, if they are empty.
For existing systems, if you would like to clean up the existing empty thumbnail folders, you can follow this procedure (for linux):
- Perform a full backup of the filesystem
- Output folders to be deleted to a file to review (run from shared-home/thumbnails):
- Review the file and make sure you're comfortable with what will be deleted
- Add the -delete switch:
- Run the script again to confirm all empty folders have been deleted: