[tahoe-dev] [tahoe-lafs] #1180: put more DYHBs into flight at once when K is larger

tahoe-lafs trac at tahoe-lafs.org
Fri Oct 22 14:57:32 UTC 2010

#1180: put more DYHBs into flight at once when K is larger
     Reporter:  zooko         |       Owner:                                                
         Type:  defect        |      Status:  new                                           
     Priority:  major         |   Milestone:  soon                                          
    Component:  code-network  |     Version:  1.8β                                          
   Resolution:                |    Keywords:  easy immutable download performance regression
Launchpad Bug:                |  

Comment (by swillden):

 Replying to [comment:1 zooko]:
 > Because that case is increasingly interesting to me nowadays since (as
 mentioned in [http://tahoe-lafs.org/pipermail/tahoe-
 dev/2010-September/005247.html this mail to tahoe-dev]), I think people
 should probably start setting {{{K}}} at least as large as the number of
 servers on their grid.

 Set {{{K}}} to the number of servers in the grid?  The e-mail you
 reference (and the analysis that I've done) recommends setting {{{M}}} to
 the number of servers in the grid and scaling {{{K}}} to achieve the
 desired level of redundancy.

 Intuition says that setting {{{K=N}}} and {{{M=K*3.33}}} should achieve
 roughly the same level of reliability for an expansion factor of 3.33 as
 setting {{{M=N}}} and {{{K=M/3.33}}}, but I haven't done the math to
 verify it.

 In any case, I think larger values of {{{K}}} and {{{M}}} are definitely a
 good idea, and getting good performance with larger values is important if
 we want to encourage people to use them.  I'd certainly use them if I had
 access to a large-enough grid to make it worthwhile.

Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1180#comment:2>
tahoe-lafs <http://tahoe-lafs.org>
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