I recently finished listening to the lastest VMware Communities Roundtable podcast and it got me thinking more about chargeback models and how to determine the chargeback for a real live production environment. It seems like we are still shooting in the dark when it comes to figuring out how to charge the consumers of our private cloud services.
I would like to offer some ideas and suggestions for how to calculate the per VM cost for storage, compute and network resources. I am very interested in this concept as my company moves toward a chargeable service model for IT. I will break this up into 3 parts so as to (hopefully) get more comments and feedback, as well as to go into more detail about each area of chargeback.
Storage chargeback not only consists of storage capacity used but also metrics of the IOPS used over a given period of time for a particular VM. As such, we need to have a base rate that takes into account capacity in GB for a particular VM that is charged per month, without any deviance, since the storage capacity is used as long as the virtual disk exists on the datastore.
In addition, the amount of storage bandwidth should be charged based on a peak IOPS or average IOPS basis. This amount varies per billing period based on the actual metrics from the storage system.
The base rate (consistent rate for storage used) should consist of the following items: Total purchase price of the storage system + support contract + power/cooling + hosting costs + personnel costs / number of years system to be used (i.e. minimum lease period) = base rate per VM (for storage)
The rate factor (conditional based on usage) should consist of the following items: Tier of storage (inverse) x number of IOPS (peak or average) = rate factor per VM (for storage)
Again, I am looking for feedback on this. If I am missed something, please let me know. What metrics are you using to determine realistic base rates and rate factors for your environment?
*Next time, we talk about chargeback for Network utilization…
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