[tahoe-lafs-trac-stream] [tahoe-lafs] #1252: use different encoding parameters for dirnodes than for files

[tahoe-lafs]

#1252: use different encoding parameters for dirnodes than for files
-------------------------+-------------------------------------------------
     Reporter:           |      Owner:  davidsarah
  davidsarah             |     Status:  assigned
         Type:  defect   |  Milestone:  undecided
     Priority:  major    |    Version:  1.8.0
    Component:  code-    |   Keywords:  preservation availability dirnodes
  frontend               |  anti-censorship
   Resolution:           |
Launchpad Bug:           |
-------------------------+-------------------------------------------------

Old description:

> As pointed out in [http://tahoe-lafs.org/pipermail/tahoe-
> dev/2010-November/005558.html this tahoe-dev subthread], if you only know
> how to reach a given file via a sequence of dirnodes from some root, then
> loss of any of those dirnodes will effectively make the file unavailable.
>
> This implies that you might want to choose the encoding parameters and
> happiness threshold to provide greater redundancy for dirnodes.

New description:

 As pointed out in [http://tahoe-lafs.org/pipermail/tahoe-
 dev/2010-November/005558.html this tahoe-dev subthread], if you only know
 how to reach a given file via a sequence of dirnodes from some root, then
 loss of any of those dirnodes will effectively make the file unavailable.

 This implies that you might want to choose the encoding parameters and
 happiness threshold to provide greater redundancy for dirnodes.

--

Comment (by daira):

 I suspect part of the difference between Zooko's and my opinion on this
 issue is that I already see the complexity of potentially having different
 encoding parameters for different objects as a sunk cost. And I agree
 completely with "Tahoe-LAFS files do NOT have reliabilities above the it-
 makes-sense-to-think-about-it level."

-- 
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1252#comment:8>
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