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> >2. the bandwidth stats are cached in the DB then retrieved again
> >   before being reported, so the mechanism is quite heavyweight.
> 
> Well, b/w accounting is the biggest issue with billing. Getting it
> right is critically important for SP's. Personally I like the
> comfort of having it in the db for later retrieval vs having it
> float in the ether until it gets picked up. Somewhere, someone has
> to persist this stuff quickly. Should this be done in Nova ... Hmm.
> I could see both arguments. It is a pretty important thing though. I
> suspect it lives there because it was done when ceilometer was but a
> glint-in-the-eye.
> 
> What would a lighter weight approach look like?


I'd expect that it would involve eagerly off-loading the b/w counters
to the ceilo pipeline (or whatever is being used to publish these data)
where it's likely to be persisted at the endpoint.

(As opposed to caching in the nova DB, then retrieving and sending 
off as a notification, which is received and re-persisted in for example
the ceilo metering store)

So there's a chance that some notifications could be dropped if for
example the ceilo collector is swamped, but wouldn't these counters
be mainly cumulative? (and if so, would a v. small loss rate be a
massive issue?)

Cheers,
Eoghan