[j-kidd]

Good article, but I think it touches too little about persistence. The trade-off of EBS vs ephemeral storage, for example, is not mentioned at all.

Getting your application server up and running is the easiest part in operation, whether you do it by hand via SSH, or automate and autoscale everything with ansible/chef/puppet/salt/whatever. Persistence is the hard part.

[crescentfresh]

Good point. We're struggling to see the benefits of EBS for Cassandra that has its own replication strategy (ie data is not lost if an instance is lost), voiding the "only store temporary data on ephemeral stores" argument.

[lowbloodsugar]

You've probably read this, but in case anyone else is considering EBS and cassandra...

"EBS volumes are not recommended for Cassandra data volumes."

http://www.datastax.com/docs/1.1/cluster_architecture/cluste...

[blakesmith]

How do you handle entire datacenter outages with ephemeral only setup? You can replicate to another datacenter, but if power is lost to both do you just accept that you'll have to restore from a snapshotted backup?

[objectivefs]

Persistence for AWS can be relatively simple if you use a distributed filesystem, such as GlusterFS (http://gluster.org) or our ObjectiveFS (https://objectivefs.com). You get a shared namespace for all your instances and persisting your data becomes as simple as writing files.