[tor-bugs] #12538 [Tor]: Make all relays automatically be dir caches

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#12538: Make all relays automatically be dir caches
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     Reporter:           |      Owner:
  cypherpunks            |     Status:  needs_review
         Type:  task     |  Milestone:  Tor: 0.2.6.x-final
     Priority:  normal   |    Version:  Tor: unspecified
    Component:  Tor      |   Keywords:  tor-guard, tor-relay, prop237,
   Resolution:           |  026-triaged-1, sebastian-review
Actual Points:           |  Parent ID:
       Points:           |
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Comment (by nickm):

 Replying to [comment:32 sysrqb]:
 > Replying to [comment:29 Sebastian]:
 > > To restate my concern from above, doing this would mean requiring all
 relays need to have ~200 MB of disk around to cache old documents, without
 need because we mainly want guards to be caches.
 >
 > Sorry, I see now you mentioned this in [comment:15 comment 15].
 >
 > Sebastian and I discussed this, and the current design is not-quite-
 right. We can certainly make every relay a dircache, but that doesn't
 avoid unnecessary consequences. As an example, this would have a
 significant impact on memory-constrained systems. As such, more precisely,
 our goal is that, after the network has sufficiently upgraded, whenever a
 client chooses a guard it should always be a dircache. This leaves two
 options, either all guards *become* a dircache (when they get the guard
 flag) or being a dircache is a *requirement* for getting the guard flag.
 The former is tricky, as arma said above, the later requires a spec
 change.
 >
 > The current plan, given this, is implementing the latter option based on
 my current patch. Step 0, add a torrc option so relay operators can
 control whether or not their relay is a dircache. Step 1, get this merged
 into 0.2.6, as planned. Step 2, write proposal amending Guard flag
 criteria. Step 3, implement proposal and merge into 0.2.7.

 Hm.  If there's a special flag you need to set in order to become a guard,
 I think that would probably be bad for the network.  I wonder if we
 couldn't have high-bandwidth relays (as determined by some criteria)
 automatically turn this on?

 We should also adjust our planned timing for amending the Guard flag
 criteria so that we don't cause a large number of Guards to disappear
 because they were running older versions or hadn't set the flag.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/12538#comment:37>
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