Red Hat ENTERPRISE LINUX 5 - VIRTUALIZATION GUIDE Manual page 143

Installing Windows Server 2008 as a fully virtualized guest
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10. Memory and CPU allocation
The Memory and CPU Allocation window displays. Choose appropriate values for the virtualized
CPUs and RAM allocation. These values affect the host's and guest's performance.
Virtualized guests require sufficient physical memory (RAM) to run efficiently and effectively.
Choose a memory value which suits your guest operating system and application requirements.
Remember, guests use physical RAM. Running too many guests or leaving insufficient memory
for the host system results in significant usage of virtual memory and swapping. Virtual memory is
significantly slower which causes degraded system performance and responsiveness. Ensure you
allocate sufficient memory for all guests and the host to operate effectively.
Assign sufficient virtual CPUs for the virtualized guest. If the guest runs a multithreaded
application, assign the number of virtualized CPUs the guest will require to run efficiently. Do
not assign more virtual CPUs than there are physical processors (or hyper-threads) available on
the host system. It is possible to over allocate virtual processors, however, over allocating has
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