ABSTRACT
This chapter introduces some essential concepts related to workload generation and methods that support workload modeling. In this context, the term workload refers to all inputs that affect the computer system's behavior, such as application programs, services, transactions, and data transfers submitted to a system. The internet is especially interesting in terms of the workload due to the temporal variation of the analyzed workload patterns. Internet workloads typically exhibit temporal changes when distinct patterns are observed at different hours of the day and different days of the week. A real workload is a timely ordered set of requests, transactions, program executions, and tasks carried out by a computer system during a production period of interest. The monitoring tools running on the load-balancer gather the number of transactions of each type, the instant of each transaction request arrival, the number of packages related to the particular transaction, the instant the reply is at the customer, and the number of packages sent.
