repair to different levels of N

[zooko]

Currently repair will try to create a number of shares equal to whatever number the file was originally created with.

It might be useful to tell repair not to go that far and produce only a few shares.

[zooko]

See also #678 (converge same file, same K, different M), which if implemented would make it also be sensible to tell repair to go further and produce more shares than the original file had.

[zooko]

The following clump of tickets might be of interest to people who are interested in this ticket: #711 (repair to different levels of M), #699 (optionally rebalance during repair or upload), #543 ('rebalancing manager'), #232 (Peer selection doesn't rebalance shares on overwrite of mutable file.), #678 (converge same file, same K, different M), #610 (upload should take better advantage of existing shares), #573 (Allow client to control which storage servers receive shares).

[zooko]

Also related: #778 ("shares of happiness" is the wrong measure; "servers of happiness" is better).

[zooko]

See new related ticket #1340 (consider share-at-a-time uploader).

[warner]

s/M/N/ to match our existing "k-of-N" terminology

[daira]

I'm confused, why would we want this? Just to decrease storage requirements?