There’s the preferredLeader property, see: 
https://lucene.apache.org/solr/guide/6_6/collections-api.html

That said, this was put in for situations where there were 100s of shards with 
replicas from many shards hosted on any given machine, so it was possible in 
that setup to have 100 or more leaders on a single node.

In the usual case, the leader role doesn’t do very much extra work, and the 
extra work is mostly distributing the incoming documents to the followers 
during indexing (mostly I/O). During query time, the leader has no extra duties 
at all. So if “heavy use” means heavy querying, it shouldn’t make any 
appreciable difference.

I would urge you to have evidence that this was worth the effort before 
spending time on it. And, the “preferredLeader” property is just that, a 
preference all things being equal. It’s still possible for a leader to be a 
different replica, otherwise you’d defeat the whole point of trying for HA.

For TLOG and PULL setups, the leader will always be a TLOG replica, so you 
could strategically place them to get what you want. In this case, the leader 
indeed has a lot more work to do than the follower so it makes more sense.

Best,
Erick

> On Oct 28, 2019, at 6:13 AM, Koen De Groote <koen.degro...@limecraft.com> 
> wrote:
> 
> Hello,
> 
> I'm looking for a way to configure my collections as such that the leader
> nodes of specific collections never share the same host.
> 
> This as a way to prevent several large and/or heavy-usage collections on
> the same machine.
> 
> Is this something I can set in solrconfig.xml? Or are there rules for this?
> 
> Kind regards,
> Koen De Groote

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