[tahoe-dev] A simple 2 nodes replication

Greg Troxel gdt at ir.bbn.com
Thu Feb 14 17:26:59 UTC 2013


thierry dijoux <tjr.dijoux at gmail.com> writes:

> After some investigations rebalance seems to work.

Your example doesn't show that.

> Here is the test :
>
> stop the 2nd node.
> Upload a file on node 1.
> Starting node 2 and do a "check --repair" => nothing.
> Now, in node1, rm .tahoe/storage/shares/de/derbnumtsxwu7rhydpxtxizd5y/1 and
> do a check --repair, the file is created on node2.

But that isn't "rebalancing", which would describe the process of
checking files to see if any do not meet the balance criteria (as shown
by shares.happy).  That was recovering from missing shares.  I suspect
if you did the repair while node2 was down that you'd be back where you started.

> I supposed the files named 0 and 1 corresponding to the index of node (in
> my case 0 => node1 and 1=>node2)

I think the files in storage are the share #.

> May i right or wrong ? I've only got 4 files, so it was "easy", but how to
> achieve this with tons of files ?

What's needed is a way to have deep-check --repair consider a file
unheatlhy if it does not meet some distribution criteria.

You might try setting shares.happy to 2 instead of 1.

The real trouble is that this line of thinking leads to incremental
complexity.  Next one wants one distribution criteria for "good enough
to place a file" and another for "good enough that we don't try to make
it better".

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