We are having 3 indexers (Indexer 1, Indexer 2, Indexer 3) on our environment, we are using them as a search head as well. We are planning to upgrade to 6.4 only one of the indexer (only Indexer 2). we have Indexer 1 as a License master. Please let me know is it possible to upgrade only one of our indexer to 6.4 and keep rest indexer are same in 6.2 version. This is not clustered environment.