Automatic rerouting of old indices

Hi,

I have 3 nodes and indices with 3 shards and one replica. I see some of my old indices have primary shards on the same node. I believe this happened during midnights, when indice was created, but some node was down. Now I can manually move shards to different nodes using cluster reroute, but I thought this should be done automatically. But this is not happening, although cluster.routing.allocation.enable is set to all. So how to achieve this? Should I use curator? And am I right thinking that having all primary shards on same node is slower than having them spread across cluster?

Thank you very much for help.

Not really, no, and certainly not if these are "old" indices that see very little indexing traffic. From a search point of view there is absolutely no difference between primaries and replicas.