[tahoe-dev] [tahoe-lafs] #778: "shares of happiness" is the wrong measure; "servers of happiness" is better

tahoe-lafs trac at allmydata.org
Mon Nov 30 01:31:02 UTC 2009


#778: "shares of happiness" is the wrong measure; "servers of happiness" is
better
--------------------------------+-------------------------------------------
 Reporter:  zooko               |           Owner:  zooko   
     Type:  defect              |          Status:  assigned
 Priority:  critical            |       Milestone:  1.6.0   
Component:  code-peerselection  |         Version:  1.4.1   
 Keywords:  reliability review  |   Launchpad_bug:          
--------------------------------+-------------------------------------------

Comment(by davidsarah):

 Replying to [comment:86 zooko]:
 >  * Also the error message that test.txt is testing for -- "shares could
 only be placed on 1 servers (4 were requested)" isn't really accurate.  It
 is hard to make it more accurate while keeping it short.  The truth is
 something like "We were able to locate or upload shares $X servers such
 that any $K of them are sufficient to download the file, but we were asked
 to make it so that there would be at least $H such servers."

 I think the message needs to be split into two cases. Technically, there
 are always at least $K-1 servers such that any $K of them will be able to
 reconstruct the file (vacuously, since there are no $K-element subsets of
 a ($K-1)-element set). However, it is confusing to say that. So, if $X <
 $K, we should use a different message, something like "We were only able
 to locate or upload shares to $S servers. We were asked to make it so that
 there would be at least $H servers, any $K of which are sufficient to
 download the file."

-- 
Ticket URL: <http://allmydata.org/trac/tahoe/ticket/778#comment:87>
tahoe-lafs <http://allmydata.org>
secure decentralized file storage grid


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