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VMware Workstation 5.5

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Disk I/O Performance Tips

Memory Trimming

Workstation uses a memory trimming technique to return unused virtual machine memory to the host machine for other uses. While trimming usually has little impact on performance and may be needed in low memory situations, the I/O caused by memory trimming can sometimes interfere with disk-oriented workload performance in a guest.

You can disable memory trimming for a guest in the virtual machine settings editor (VM > Settings > Options > Advanced). In the Settings section of the Advanced panel, select Disable memory page trimming.

Page Sharing

VMware uses a page sharing technique to allow guest memory pages with identical contents to be stored as a single copy-on-write page. Page sharing decreases host memory usage, but consumes system resources, potentially including I/O bandwidth.

You may want to avoid this overhead for guests for which host memory is plentiful and I/O latency is important. To disable page sharing, add the following line to the virtual machine configuration (.vmx) file:

sched.mem.pshare.enable=FALSE option

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