Here is an image that shows what the Amazon VPC we're thinking about using looks like:
http://i.imgur.com/OUe1i.png We would like to configure a 2 node Cassandra cluster in the private subnet and a read/write web application service in the public subnet. However, we also want to span the Cassandra cluster across from the Virginia VPC to a California VPC and have 2 Cassandra nodes in the private subnet in Virginia and 1 node in the private subnet in California. Amazon states that EC2 instances in Virginia’s VPC can communicate with EC2 instances in California’s VPC as long as all communication takes place over the internet gateway of each VPC and uses Elastic IP addresses as the specified source or destination address. But Amazon also says that “EIP addresses should only be used on instances in subnets configured to route their traffic directly to the Internet Gateway”. So, by this they must mean the public subnet in the diagram above. Amazon goes on to say “EIPs cannot be used on instances in subnets configured to use a NAT instance to access the Internet.” It looks like we cannot have a Cassandra cluster spanning two Private Subnets in two different regions. Can somebody with VPC experience confirm this? Also has anybody successfully deployed a Cassandra cluster in private subnets spanning multiple regions? Any tips from your experience? How did you find the latency over VPCs and gateways across regions? - Sameer Accenture Technology Labs
