[tahoe-dev] servers-of-happiness default of 7 prevents first-time installation from working "out of the box"

Kevan Carstensen kevan at isnotajoke.com
Wed Jun 16 00:01:30 UTC 2010


At 2010-06-15 17:14 (-0600), Zooko O'Whielacronx wrote:

> With the current code base in Tahoe-LAFS 1.7β, the default setting for
> servers-of-happiness is 7:
> 
> http://tahoe-lafs.org/trac/tahoe-lafs/browser/trunk/src/allmydata/client.py?rev=4193#L110
> 
> But when someone follows the quickstart instructions:
> 
> http://tahoe-lafs.org/source/tahoe-lafs/trunk/docs/running.html
> 
> They will probably create only one server, so then when they try to
> upload something they will get an UploadUnhappinessError.
> 
> One possible solution to this would be to lower the default
> servers-of-happiness from 7 to 1. This would require us to also lower
> the default number of shares needed from 3 to 1, because the current
> code won't let you have a servers-of-happiness lower than your
> number-of-shares-needed:
> 
> http://tahoe-lafs.org/trac/tahoe-lafs/browser/trunk/docs/configuration.txt?rev=4283#L247
> 
> Another solution would be to instruct people in running.html to create
> seven servers. By the way, running.html is due for an overall, per
> ticket #1024.

Another possible solution, and one that has a patch in #1080 [1], is to
alter running.html to advise users with smaller grids to alter the
parameter in tahoe.cfg to whatever is appropriate for their use.  It
seems to me that setting k=1 and happy=1 by default would cheat users
who observe that it "just works" out of the box and never touch the
configuration file out of a lot of the benefits that properly set
encoding parameters can give.  Altering running.html to advise users to
make 7 servers is better in this regard, but more work for the user.
Advising the user to look at and change the encoding parameters is a
nice middle ground, and encourages the user to figure out what the
correct K, N, and happy are for their grid as a pleasant side-effect.

[1] http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1080
-- 
Kevan Carstensen | <kevan at isnotajoke.com>



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