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Apache Workload

This workload consists of a Linux client application and a Linux server application that execute on the same z/VM system and are connected by a guest LAN (QDIO simulation) or Virtual Switch (VSwitch). The client application is the Application Workload Modeler product (AWM), imitating a web browser. The Linux server application is a web server that serves static HTML files. Each AWM client application can have multiple connections to each server application. Consequently, the total number of connections is the product of these three numbers (servers, clients, client connections per server). For each connection, a URL is randomly selected. AWM uses the same random number seed for all client connections.

This workload can be used to create a number of unique measurement environments by varying the following items:

  • number of server virtual machines
  • number of client virtual machines
  • number of client connections per server
  • number of files
  • size of the files
  • location of the files
  • size of the server virtual machine
  • number of virtual processors for the client
  • number of virtual processors for the server

Performance data for Apache workload measurements are collected from the start of the workload until the last AWM client has reported completion to the AWM client controller. In some measurements, characteristics during the steady-state period (all clients are active) are more suitable for explanations. When used, they will be specifically identified as steady-state values.

Here is a list of unique workload scenarios that have been created and measured:

  • A non-constrained workload can be created by using a small number of small URL files.

  • A Linux I/O workload scenario can be created by using a set of URL files that greatly exceeds the virtual storage size of the Linux server virtual machines.

  • Preloading all the URL files into a large z/VM Minidisk Cache (MDC) creates a workload scenario with a lot of Linux I/O but without any real I/O. Depending on the scenario desired, MDC can be configured either to use only central, or only XSTORE, or a mix.

  • A z/VM storage usage workload can be created by using a large set of URL files that all fit in the Linux page caches (sometimes aka file caches) of the server virtual machines.

  • A z/VM expanded storage paging workload can be created using the previously described storage usage workload in a configuration that has a lot of expanded storage but doesn't have enough real storage to support the working set characteristics of the application.

  • A z/VM mixed paging workload can be created using the previously described storage usage workload in a configuration that has a large DASD paging subsystem but doesn't have enough real storage and expanded storage to support the working set characteristics of the application.

  • A z/VM DASD paging workload can be created using the previously described storage usage workload in a configuration that has a large DASD paging subsystem, no expanded storage, and doesn't have enough real storage to support the working set characteristics of the application.

  • A z/VM Single System Image mode (SSI-mode) workload can be created by running up to four separate sets of client/server pairs. Within a set there can be multiple clients communicating with multiple servers. The four sets run independently of each other thus allowing the workload to be equally distributed across a 2-member or a 4-member SSI cluster. The four sets may also run in the same z/VM image. Apache SSI-mode requires the Linux guests to be connected by VSwitch.

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