The following documentation pages say that it is not recommended to use vnodes for Solr/Hadoop nodes:
http://www.datastax.com/documentation/datastax_enterprise/4.0/datastax_enterprise/srch/srchIntro.html http://www.datastax.com/documentation/datastax_enterprise/4.0/datastax_enterprise/deploy/deployConfigRep.html#configReplication
What is the exact problem with using vnodes for these node types? I inherited a DSE setup wherein the Search nodes all use vnodes, and I wonder if I should take down the cluster and disable vnodes. Is there any harm in leaving vnodes enabled in such a case?
It is primarily a performance concern with DSE/Search since a query needs to fan out internally to enough nodes (or vnodes) to cover the full range of Cassandra rows in the DC, that's a lot more sub-queries when vnodes are enabled.
But, if your performance with vnodes in a DSE/Search DC is acceptable, then you have nothing to worry about.