I found this discussion and noticed that the error  "Impala is not supported for RHEL7" can appear in CM 5.11 if you try to install Impala via parcel. Since 2015 and on, Impala is included in the main CDH parcel, and is simply added as a service to the cluster.  If you try to add via parcel on RHEL7 (or centos7), you are in effect trying to add an old version (2.0 or earlier) of Impala, and in that case, the statement  "Impala is not supported for RHEL7" is actually true.    I expect this misleading error message will occur for any attempt on any CM ver. to add Impala via parcels on RHEL7.   I hope this clarification helps someone.   ... View more

Director itself doesn't care whether the AMI uses HVM or PV, but EC2 instance types are often only compatible with a single virtualization type. As you say, Amazon recommends HVM for the R3 instance type.   Here's a pretty good blog post on virtualization types: http://cloudacademy.com/blog/aws-ami-hvm-vs-pv-paravirtual-amazon/   That describe-images command is just an example, and you can change the parameters to suit the particular AMI details you are looking for.   ... View more