[tahoe-lafs-trac-stream] [tahoe-lafs] #1209: repair of mutable files/directories should not increment the sequence number

[tahoe-lafs]

#1209: repair of mutable files/directories should not increment the sequence
number
-------------------------+-------------------------------------------------
     Reporter:  gdt      |      Owner:  davidsarah
         Type:  defect   |     Status:  assigned
     Priority:  major    |  Milestone:  soon
    Component:  code-    |    Version:  1.8.0
  mutable                |   Keywords:  repair mutable preservation space-
   Resolution:           |  efficiency
Launchpad Bug:           |
-------------------------+-------------------------------------------------

Comment (by davidsarah):

 Replying to [comment:14 Brian]:
 > We really only need a new version if there are multiple competing
 versions with the same sequence number, and if that sequence number is the
 highest seen.

 Counterexample: suppose there is a recoverable version with sequence
 number S, and an unrecoverable version with sequence number S+1. (There
 are no versions with sequence number >= S+2.) Then, the new sequence
 number needs to be S+2, in order for clients not to use the shares from
 S+1. Deleting the shares with sequence number S+1 is also possible but
 inferior, since sequence numbers should be monotonically increasing to
 minimize race conditions.

 > > We should add a method to {{{ServerMap}}} that tells us whether a new
 version is needed or not.

 +1.

-- 
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1209#comment:15>
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