Colors in the admin page

Question

I'm using Solr 4.0 (release from Oct, 12) and using two shard cluster with shard replicas example from http://wiki.apache.org/solr/SolrCloud. In my ~cloud page I can see the cluster's chart, for some reason 3 of shards/replicas are green and one of them is red. Sometimes they look different - some of them are green, grey, etc...

Any ideas what does those colors mean?

Answer 1

Check the Screen Shots attached @ SOLR-3915