Branimir Lambov commented on CASSANDRA-12777:

Thank you for the changes, this looks good to me.

One last thing is bothering me about the takeover situation (and sorry I did 
not get around to writing about it earlier): in greater-than we set to 0.75, 
but [on equal (or close to equal) we let the new take completely 
 This feels inconsistent and (at least to me) potentially problematic (it may 
also be the reason why we see no effect on the simulation). Could we limit the 
fraction of the range that can be taken over instead?

> Optimize the vnode allocation for single replica per DC
> -------------------------------------------------------
>                 Key: CASSANDRA-12777
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12777
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Dikang Gu
>            Assignee: Dikang Gu
>             Fix For: 3.x
> The new vnode allocation algorithm introduced in CASSANDRA-7032 is optimized 
> for the situation that there are multiple replicas per DC.
> In our production environment, most cluster only has one replica, in this 
> case, the algorithm does not work perfectly. It always tries to split token 
> ranges by half, so that the ownership of "min" node could go as low as ~60% 
> compared to avg.
> So for single replica case, I'm working on a new algorithm, which is based on 
> Branimir's previous commit, to split token ranges by "some" percentage, 
> instead of always by half. In this way, we can get a very small variation of 
> the ownership among different nodes.

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