Question about Reserved Instance Pricing

1. If I sign a contract stand of 3 year, with cluster have 1 node of dc2.8xlarge. When I grow my cluster by adding new node of dc2.8xlarge, so is this new node will have same price with the first one?

So, I may be wrong, but I think you will have one node priced as a reserved instance, and one node priced as a normal, on-demand instance.

2. If I sign a long term contract (example 3 year) but I only use my cluster 20 hour per day (I can shutdown my cluster in unused time), so is this the cost will cut down for the hour that I don't use?

I may be wrong, but i think it makes no difference - there is no benefit to turning shutting the cluster down.

Think about it - one of the reservation options has no up-front, but you pay 21% less, and that arrangemen lasts for one year. If you only paid when the cluster was running, wouldn't that just be a general 21% discount for everyone? :-)

The docs says reserved instances are for 'steady-state workloads", which (although I may be wrong - I don't know, I'm just saying now what I think) is an obscure way of saying you keep paying when the instance is shut down.

The key thing to understand is: Reserved instance pricing is a billing concept. It does not affect the operation of your clusters.

1. If I sign a contract stand of 3 year, with cluster have 1 node of dc2.8xlarge. When I grow my cluster by adding new node of dc2.8xlarge, so is this new node will have same price with the first one?

No, the additional node(s) will charged at the on demand rate unless you purchase additional reserved instances. Note that the minimum size for 8xlarge clusters is 2 nodes.

2. If I sign a long term contract (example 3 year) but I only use my cluster 20 hour per day (I can shutdown my cluster in unused time), so is this the cost will cut down for the hour that I don't use?

No, the reservation is charged regardless of whether a cluster is in use.

Thanks Toebs2, joeharris76-AWS very much for your support.