It's basically maintenance-free, and if you got trouble, you can ask in Issue Tracker https://gitlab.com/gitlab-org/gitlab-ce/issues. We can advise how you can recover your instance case-by-case. (Also, there is a feature for backup your local data to cloud storage https://docs.gitlab.com/ee/raketasks/backup_restore.html. This is useful in case your machine'HDD died suddenly)

To troubleshoot your problem smoothly, I'd advise not to modify your GitLab instance intentionally, for instance, applying own custom patch, changing database schema, etc.