We have switched Thumbor/thumbnails to be active/active T201858, AFAIK we should be able to serve originals too in an active/active fashion. Said feature is driven by FileBackend being in "sync" mode between its eqiad and codfw swift backends.
A list of things to test/verify for completion:
- Verify all FileBackend activity is effectively sync (e.g. math/captcha/score renders)
- Run active/active originals for a limited amount of time, verify uploads work as intended from both eqiad and codfw