Display disk space consumed by Mastodon.
Use tootctl utility that can be executed from the command-line interface.
mastodon@mastodon:~/live$ RAILS_ENV=production ./bin/tootctl media usage
Attachments: 2.09 GB (516 KB local) Custom emoji: 58.9 MB (9.58 KB local) Preview cards: 165 MB Avatars: 1.28 GB (74.9 KB local) Headers: 2.86 GB (357 KB local) Backups: 0 Bytes Imports: 0 Bytes Settings: 0 Bytes