 Chapter 4: Managing Cloud Workloads and Services 39 Management  in this context refers to how resources are  assigned in order to process workloads. Assignments may be  based on resource availability, business priorities, or event  scheduling. The idea of managing workloads has been around for  decades. In the unified mainframe-computing era, workload  management was pretty straightforward. When a task had to  be executed, a job was scheduled to run on that system. The  instructions for running that task or job were typically written  in a complex job-control instruction language. This set of commands helped the IT organization carefully plan the execution of workloads. If a mission-critical workload required  a huge amount of time to run, a set of instructions could be  established to stop that workload and allow another workload  to run. When the second workload finished executing its task,  the long-running workload could resume. The challenge in managing any workload is making sure that  it can be executed and delivered at the right performance  level. It involves understanding processing requirements,  modeling resources, and determining capacity. The principle  is not that difficult if you’re dealing with applications running  on one server or even in a homogeneous cloud environment.  And, if you’re using just a public cloud provider then that  provider manages your workloads. However, as IT infrastruc- tures become more complex and heterogeneous, such as in a  hybrid environment, this becomes harder to do. Things get a lot more complicated in a hybrid cloud environment. With the advent of a hybrid cloud, many more  applications and services exist across different countries that  have to run. Some workloads may be permanent and need to  These materials are the copyright of John Wiley & Sons, Inc. and any  dissemination, distribution, or unauthorized use is strictly prohibited. Seeing Workload Management  in a Hybrid Cloud Looking at the Principles of  Workload Management