For its own pricing calculations, Amazon came up with the notion of what it called its Elastic Compute Unit or ECU. One EC2 Compute Unit provides the equivalent CPU capacity of a 1.0GHz-to-1.2GHz processor. But this unit may or may not translate well for other providers.
CloudPriceCalculator.com says it addresses three obstacles when comparing the price of infrastructure-as-a-service cloud offerings:
- Translate compute capacity to Amazon's ECU's based on 1 ECU = 400 Passmark. (cpubenchmark.net)
- The CPN (Cloud Price Normalization) index simply adds compute, memory, storage, and bandwidth and divides by price
- goCipher created an offer at DomainGurus duplicating several of Amazon instances
The CloudPriceCalculator uses what it calls a simple index to compare IaaS cloud computing offers, and its CPN reflects the quantity of cloud resources that one can buy for $1,000.
The CPN also unwinds some of the confusion about total cost that arises from the many a la carte components of cloud offers. As an example, the company states that the cost of bandwidth tends to represent a significant monthly cost with vendors charging anywhere from 12 to 22 cents per gigabyte. While most of the vendors charge only for outbound bandwidth, some charge for both inbound and outbound bandwidth. There exists a range of other a la carte charges as well, such as for IP addresses or persistent storage that can affect pricing. And there are significant differences in the strength and cost associated with the various support offers from one provider to the next.