In order to ensure the accuracy of measurements with regard to virtualised environments (for capture of prediction purposes), it is necessary that the virtualisation technology be subject to limitations:
• Attempt to obtain measurements in a non-virtualised environment. If a non-virtualised environment is not possible, then the Virtualisation overhead must be established with regards to the specific situation. This can be established with the comparison of transaction measurements captured in a virtualised and non-virtualised environment.
• Ensure that SMT (simultaneous multi-threading) is switched off on the application servers.
• Only physical processor configurations should be used. Logical processors are to be avoided.
• The application under test should operate within a virtualised environment which is isolated from the impacts of other virtualised applications. Isolation should occur at the processor, disk and memory level.
o The number of CPUs assigned should be fixed and dedicated to the application only.
o Logical disks should operate on dedicated physical disks.
o Dedicated memory should be made available to the application under test.
• If running on a virtualised environment, it would be preferable to ensure that other applications are not running simultaneously, to keep unwanted network impact activity to a minimum.
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