tips about running HBase in EC2.
1) Use private dns addresses in config files such as hdfs-site.xml, hbase-site.xml. On ec2 Ubuntu instances java’s getHost() gets resolved to the private dns addresses.
2) Use c1.xlarge or bigger node to start with. I have seen Andrew Purtell (HBase committer) recommending this on HBase mailing list. We have tried m1.large machines. It has worked well for us when our traffic was small. We are hitting HBase in real time. As traffic started increasing we started getting CPU maxouts. Currently we use c1.xlarge machines.