[tahoe-dev] Upload misunderstanding or bug?

Kyle Markley kyle at arbyte.us
Wed Jul 28 04:58:53 UTC 2010

I'm not sure whether I'm misunderstanding something, or whether I've found
a bug.

I've been playing with my home grid a lot recently.  When I first set up
this grid I was using encoding parameters 2/3/4 but I changed this to 2/4/4
after the first couple days.  When I filed ticket #1130 I believed I was
running into some kind of interference from the fact that I had previously
been using 2/3/4, and was just hitting a problem in changing my encoding
parameters -- which most people probably don't do.

I needed a workaround, so I thought of one.  Since I wanted to use 2/4/4,
shares.happy == shares.total, and I had exactly 4 storage nodes in my grid,
so I reasoned that I should expect every storage node to get exactly one
share.  My workaround was to write a script that I ran on each storage
node.  The script identified storage indexes with more than one share, and
deleted those storage indexes.

Firstly, was my workaround correct, at least in principle?  (It sure
seemed to be effective in practice.)

I'm writing now with an unsettling observation.  The upload errors
eventually came back, and if I re-run the script it again identifies
storage indexes with more than one share!  Shouldn't that be impossible? 
I'm consistently running with 2/4/4 now, so shouldn't every storage index
always have exactly one share?

Does this suggest that there's (still) a bug in share placement that
causes unreported happiness failures?  Or might I still somehow be seeing
some kind of leftover from my 2/3/4 encoding days?

Kyle Markley

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