Performance Testing, LoadRunner Tips&Tricks

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General: Virtualization with LoadRunner

There was the question posted in the Yahoo discussion group on the topic of virtualization with LoadRunner. That is to use virtualization tools such as VmWare and its support and compatibility with LoadRunner.
James Pulley who often posts in the group came together a list of recommendations with regards to his experience in such a topic here. The recommendations consist of what could be installed on the virtual machines. I personally appreciated that he put in these information.
I believed that the recommendations will be very useful for individuals or organisations looking for some answers with the proliferation of the virtualization tools and therefore extracted the content of the discussion and publish here.
The recommendation by James were in order of the least influenced to the most influenced by virtualization.
The core issue associated with virtualization is the state of the virtualized system clock which is inconsistent in operation, so much so that time critical events do not illustrate reliable behavior Mercury Analysis. This is a very easily virtualized tool. There are no time critical components associated with the analysis engine, since all of the data has been collected by other hosts during the execution of the performance test. This virtualized instance works best when the data store for the testr esults is in a Microsoft SQL Server database as opposed to the default datastore of a Microsoft Access formatted data file. With the change inl icensing with 8.1, this item can be promiscuous in its distribution and is no longer limited to just a single copy with a controller purchase.
LoadRunner Virtual User Generator
As the workbench for the script development, there are very few time critical events associated with the development and the testing of scripts. Virtualized forms of VUGEN work best on platforms which have hardwarevirtual machine extensions, such as the latest versions of the Intel CoreDuo processor and their AMD equivalents. Hyperthreaded machines seem to show in consistent performance as well - There is a knowledge base article on this hyperthreaded issue in the Mercury knowledge base. Timing may be a little off in the log due to the clock issue noted above, but other than thisissue, the VUGEN operates very well in a virtualized form. As with the Analysis engine, with the change in licensing with 8.1, this item can be promiscuous in its distribution and is no longer limited to just a singlecopy with a controller purchase.
LoadRunner Controller
As we move into the controller timing becomes a more critical item. The controller itself can be virtualized without an issue, but because thetiming record information collected is as an offset to the beginning of thetest, an inconsistent clock on the controller can become an issue formonitor data with offset timestamps may not reflect the actual system clock.
Load Generator/Injector
This is a layer which suffers from the most influence from the inconsistent clock issue for time critical events within a virtual machine and of all ofthe layers, this is the one which should be virtualized the least. The best test design would dictate that all of your generators have an identical hardware and software profile, a very difficult item to achieve invirtualized form which suffers from a virtualized CPU and a virtualized system clock.This time critical items is not something which would just impact LoadRunner. It also impacts other time critical processes, such as inability to run some functions for conferencing in virtualized PBXs.
Related Topics:
References extracted from the discussion topic:

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