[tor-bugs] #4387 [Analysis]: How much GB does a useful relay push per week?

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#4387: How much GB does a useful relay push per week?
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 Reporter:  runa      |          Owner:  karsten
     Type:  task      |         Status:  new    
 Priority:  normal    |      Milestone:         
Component:  Analysis  |        Version:         
 Keywords:            |         Parent:         
   Points:            |   Actualpoints:         
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Changes (by karsten):

  * component:  Tor Cloud => Analysis


Comment:

 (Changing the component to Analysis which fits better IMO.)

 The analysis how much traffic a bridge should be able to push per week to
 be useful is different from this analysis.  Bridges are chosen more or
 less uniformly, or at least not dependent on their bandwidth.  The idea of
 the analysis was to make sure that a cloud bridge, that is chosen with the
 same probability as non-bandwidth-limited bridges, has enough bandwidth to
 serve at least an average number of users.  If there are potentially lots
 of cloud bridges with a certain bandwidth setting, they shouldn't be
 useless by design.

 The situation is different for relays.  Relays are chosen based on their
 bandwidth capacity, among other things.  A relay is the more useful the
 more bandwidth it has.  Maybe there's a bandwidth limit below which it's
 not worth including a relay in the consensus, because it would only bloat
 the directory and keep the bandwidth scanners busy.  But I don't think
 we're looking for that number here.  (You don't want to create cloud
 relays that have just enough bandwidth that we don't want to throw them
 out of the network, right?)

 Here's a somewhat different analysis that may or may not answer your
 question: how much bandwidth does an ''average'' relay push per week?  If
 you configure a cloud relay to push this much bandwidth you'll end up with
 an average relay.  Whether that's a ''useful'' relay or not is a different
 question.  It probably is, but a relay with fewer bandwidth might already
 be useful, too.

 And here are the results: The total bandwidth pushed by all relays during
 one week (October 28 to November 3) was 583 TiB/wk or 0.99 GiB/s.  There
 were on average 2375 relays in the consensus during that time.  Hence, an
 average relay pushed 251 GiB/wk or 436 KiB/s.

 So, I could imagine that a cloud relay pushing 436 KiB/s would be useful,
 but at the same time too expensive.  A cloud relay with half or a quarter
 of that bandwidth would probably be useful, too.  But that's not a
 question I can answer using statistics.

 Maybe we should turn the question around: What's the maximum bandwidth
 that a cloud relay can push per week before becoming crazy expensive?  If
 it costs ten times the amount to run a cloud relay that pushes one tenth
 of the bandwidth that a rented virtual server pushes, maybe it's a bad
 idea to offer cloud relays.  (Also consider the development effort
 required to offer and maintain cloud relays.)

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4387#comment:1>
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