Ceph » rgw

- orthogonal to operations logs
- only aggregate user bandwidth usage (read, write) per date
- rgw sends a periodical update to the backend of user's usage
- admin command to get all bandwidth from a specific date up to a specific date
- admin command to trim user log

implementation:
- bandwidth info is kept in per-user object (actually, on more than one object to spread user load)
- info is kept on object's omap; date (epoch) as key, read and write usage as value
- new class method to add bandwidth info for a specific timestamp
- rgw aggregate bandwidth info per user and flushes that periodically to backend
- rgw rounds timestamp to nearest day/hour/minute -- probably hour?
- a new class method to delete bandwidth info for a specific timestamp
- radosgw-admin command to get user bandwidth info, by iterating over all the possible log objects for that user and aggregating the info