[tahoe-dev] [tahoe-lafs] #1092: shares.happy is the wrong name of the measure

[tahoe-lafs]

#1092: shares.happy is the wrong name of the measure
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     Reporter:  zooko           |       Owner:  warner          
         Type:  defect          |      Status:  new             
     Priority:  minor           |   Milestone:  eventually      
    Component:  code-nodeadmin  |     Version:  1.7.0           
   Resolution:                  |    Keywords:  usability upload
Launchpad Bug:                  |  
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Comment (by gdt):

 -1 on the servers.happy.

 If we're going to change, I think it would be good to also pick a
 different word than happy.  There's an important concept lurking under a
 seemingly flippant word.

 bWhat's really going on is that this single variable is a rough first cut
 at ensuring that there is adequate redundancy based on some policy and
 some knowledge of physical and administrative correlation among servers.
 I see the 3/7/10 values as very closely linked, and changing shares to
 servers makes that less clear.

 I do agree that shares.happy gives the wrong impression.   So I'll suggest
 "shares.independent", with the meaning being "the minimum number of shares
 that must be on independent servers".  I think that's what is meant, and
 this keeps the parallelism of shares.* and clarifies this variable.   One
 could have shares.independent and shares.independent-target, but I'm not
 sure independent-target needs to be different from total.

 The current ordering gives the impression that shares.needed are
 shares.total are more independent than they are.   So perhaps
 "shares.coding = (3, 10)" would be better than two variables.   (I am
 under the impression that I can't just set shares.total to 12 and
 reconstruct those missing sh10, sh11 without having to recode the entire
 file; if I'm confused on that point this paragraph is invalid.)

 3/7/10 seems reasonable, and I've been using 2/5/7.   I don't think it
 makes sense to talk about the right value of
 shares.independent/shares.happy without considering the whole 3-tuple.

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1092#comment:2>
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