I looked at it some before IndexTank was bought (and I've done a reasonable amount of Solr work).
The biggest conceptual difference seemed to be that IndexTank was specifically written to autoscale - it was designed from the ground up to run on cloud providers, and to instantiate new resources as needed. It also has no central point of failure.
Solr Cloud (and things like Solandra) deliver some of this functionality to Solr.
The biggest conceptual difference seemed to be that IndexTank was specifically written to autoscale - it was designed from the ground up to run on cloud providers, and to instantiate new resources as needed. It also has no central point of failure.
Solr Cloud (and things like Solandra) deliver some of this functionality to Solr.