sshellswell
Contributor
Contributor

Reports & Rounding

Hello,

We are using vCenter Chargeback 2.5 and using it for both vCloud Director 5.1 hierarchies and also normal vCenter hierarchies. We have noticed some unusal results and would like to seek opinion on them please.

(1) When running a Cost report, with a billing model/policy based on used thin disk storage (ie: on a normal vCenter hierarchy), I get a single figure for the whole month. For example, the report says the VM used 180.34GB of thin disk in the month.


However, when I run a Usage report for the same month and the same VM, I get a detailed breakdown of each time the disk changed - sometimes higher than 180.34 and sometimes lower. My expectation would have been that the Cost report would have included all the changes in disk, but it only includes a single figure. How is the single figure calculated or relate to the actual changes?

(2) When I run a cost report, for example for all of March, the report shows usage for the whole month, not just the part of the month that has taken place, but also all the days yet to come to the end of the month. How is this usage into the future being determined? I would have expected the report to show zero usage into the future.

(3) In terms of rounding, decimal places and significant figures used in chargeback - I know that Rate Factors can be upto 2 decimal places and Base Rates upto 4 decimal places. My question relates to at what point the maths calculations done by Chargeback are rounded before presenting the final results. For example, does Chargeback first multiply the base rate * rate factor, round that to four decial places, and then multiply by units used and number of hours in effect, and then round the final answer to 2 decial places? OR does chargeback multiply the base rate * rate factor * units used * hours in effect and just round the final answer to 2 decimal places? ie: We know there is rounding to 2 decimal places in the final prices in the report - are there any times mid-calculation where chargeback performs any rounding?

Said differently, we can enter 4 decimal places for the base rate, if the rate factor would make the resulting per unit per hour price have 5 decimal places, is the calculation for the cost based on this or a price rounded to 4 decimal places?

Many thanks in advance

Steve

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