To understand how virtual machine resources are being used in your organization, follow the money.
Assigning costs to IT assets in the virtual world is so different from the physical-only model that data centers are leaving behind that special tools must be brought in to sniff out the money trail. Thus far, the drastic cost reductions made possible by server consolidation, along with the complexity that virtualization introduces in the form of easy virtual machine migration among physical assets have resulted in a meager choice of chargeback tools.
Enter VMware vCenter Chargeback version 1.6.1, which was released in July and has a suggested price of $1,250 for a 25 VM pack. vCenter Chargeback can actually be used for either showback or chargeback.
Chargeback and Showback
Before getting into the mechanics of vCenter Chargeback, it's important to understand the difference between chargeback and showback and when an IT manager might consider one approach over the other.
Formal chargeback, according to most vendors in the space, is fairly uncommon because the cost numbers provided usually must conform to generally accepted accounting principles. These principles are quite strict when it comes to associating costs with physical assets including servers, storage arrays and network equipment, which have definite depreciation rates. Further, many of these physical assets have come with tax implications that govern how the value of the equipment is measured.
For example, if a virtual machine runs on physical server A and then moves to physical server B, neither of which are at the same point in the depreciation process, it is a nontrivial problem to figure out how much to charge the department using the virtual machine.
Furthermore, a practical chargeback system must be integrated with an internal accounting system so that bills can be presented for payment.
Showback is an informal way of associating estimated costs for virtual machine operation without any money changing hands, thereby avoiding the sticky accounting rules. Reports can be provided to managers as a guide to budgeting decisions without entering the regulated world of tax accounts.
How We Tested
I installed the vCenter Chargeback application on a virtual machine running Windows Server 2003 R2 in the eWEEK Labs VMware vSphere 5 test environment. The physical hosts were a mix of Hewlett-Packard and Acer systems. After installing Microsoft SQL Server 2008 on the virtual machine, I installed vCenter Chargeback and configured it to connect to our vCenter Server.
I started with a simple fixed-cost model by defining a template where I filled in values for rate factors. IT managers will need to work with facilities and accounting staffs to ensure that the myriad detailed costs are entered correctly. Organizations that have facilities spread across geographic regions should consider that costs for various resources would vary by region. vCenter Chargeback can take these variations into account, but that means that IT will need to input these cost factors at set-up time.
The vCenter Chargeback model uses two user-defined modules called billing policy and base rate to determine costs. IT managers who are new to performing chargeback should plan on spending several hours each month for at least two to three months making adjustments to the base rate and rate factors in order to fine-tune the cost model. In my case, I entered conservative base-rate information for a number of computing resources in my environment, including CPU (measured in GHz per hour), disk reads and writes, memory (measured in GBs per hour), network I/O and storage.
At the end of the configuration process, vCenter Chargeback used the information I provided to run reports on my VM usage as monitored by the vCenter Server.
vCenter Chargeback reports are comprehensive in scope and will take some getting used to for IT managers who are new to chargebacks. For example, because asset use is measured by the hour and varies by the time of day, vCenter Chargeback is able to prorate usage in order to provide fairly accurate billing information. Accuracy will increase the longer the virtual machine is running as most vCenter Chargeback measures are hourly, not by the minute.
I was also able to use vCenter Chargeback to create variable-cost reports. These reports required more extensive cost information and schedule data. I used the variable-cost reports modules to compare operational costs across different times of the day and different geographic locations.
vCenter Chargeback administration should be adequate for most organizations. I was able to create users who ranged from super users with total system access to report generators who were limited to running predefined reports.
It was also possible for me to define multiple reporting hierarchies so that user administrative and reporting rights were limited to systems for which they had a need to see cost data. IT managers will need to pay attention to how users are provisioned to ensure that they see only data to which they are entitled.
Although ad hoc reporting is possible in vCenter Chargeback, automated reports are the mainstay of the system. I was easily able to set up scheduled reports so that users could see how much they were spending on virtual machine resources. Over a short amount of time, vCenter Chargeback is a tool that will likely help IT and business managers control costs and wring the most use out of their virtualized resources.