SplitShard Replica Placement

[Chris Ulicny <cu...@iq.media>]

Hi all,

I've run into an issue with solr 6.3.0 where the splitshard command placed
both replicas of the new smaller shard on the same node, and I was curious
as to whether the behavior should be expected or not.

Without having dug into the source code, this is what I've observed
splitshard doing until now for a 2 replica setup (1 leader, 1 follower).
The leader replica splits into the requested number of new shards on the
same node. Then the second copy of the new shards are created on other
nodes which may or may not be the same node that the original follower
replica was located on.

How does solr determine where to put the new follower replicas, and is
there a way to prevent it from colocating the leader and the follower of
the new shards?

Thanks,
Chris