Cloud Services For Dummies, IBM Limited Edition  18 Licensing Metering Considering a private IaaS These materials are the copyright of John Wiley & Sons, Inc. and any  dissemination, distribution, or unauthorized use is strictly prohibited. ✓ The company needs to control access because of security  concerns. ✓ The company may require that business critical applications demonstrate predictable performance while minimizing risk. ✓ The company sees itself as a service provider to its customers and partners. A company would choose a private IaaS over a public one for  three compelling reasons: Metering  ensures that users are charged for the resources  they request and use. This metering to assess the charges for  the IaaS services begins when the instance is initiated and  ends when the instance is terminated. In addition to the basic  per-instance charge, the IaaS provider may include charges  for storage, data transfer, and optional services like enhanced  security, support, or advanced monitoring. The use of public IaaS has led to innovations in licensing and  payment models for software you want to run in your cloud  environment (not the license between you and your cloud  provider). For example, some IaaS and software providers  have created the Bring Your Own License (BYOL) plan so you  have a way to use your software in both traditional or cloud  environments. Another option is Pay As You Go (PAYG),  which generally integrates the software licenses with the on-demand infrastructure services. compute. A typical IaaS contract has some level of service  guarantee. At the low end, a provider may state that the company will do its best to provide good service. Depending  on the service and the price, you may contract for 99.999  percent availability. The level of service you require depends  on the workloads you’re running. We talk more about service  levels in Chapter 5.