Pretty confident that isn't it. S3 was returning InternalErrors for 22 seconds before it started timing out and/or returning 503s to all my requests.
I'd bet that something broke (causing InternalError responses) and then nodes started marking themselves as failed (causing the timeouts and 503s soon after).
I'd bet that something broke (causing InternalError responses) and then nodes started marking themselves as failed (causing the timeouts and 503s soon after).