Features | Documentation | Knowledge Base | Discussion Forums
Virtual Machine Memory Size
The first configuration parameter you can set is the size of an individual virtual machine's memory. Set this configuration parameter for the virtual machine in the virtual machine settings editor (VM > Settings > Memory). The guest memory size should not be set lower than the minimum recommendations of the operating system provider.
The New Virtual Machine Wizard sets reasonable defaults for the memory size of a virtual machine, based on the type of the guest operating system and the amount of memory in the host computer. This value also appears in the virtual machine settings editor as the recommended memory value.
If you are not familiar with the topic, start with Duncan Epping's article HA Deepdive and review the VMware HA Admission Control section of the vSphere Availability Guide. What these documents and articles do not tell us is how this slot size translates to the Available Slots as show in the Advanced Runtime Info of vCenter 4.1. 25 Memory – Best Practices Avoid high active host memory over-commitment.No host swapping occurs when total memory demand is less than the physical memory (Assuming no set limits) Right-size guest memory, avoid guest OS swapping Ensure there is enough vRAM to cover demand peaks Use a fully automated DRS cluster.Test that vMotion works.
The virtual machine settings editor also shows a value for the maximum amount of memory for best performance. If you have only one virtual machine running on the host and you set virtual machine memory to this value, the virtual machine can run entirely in RAM. A virtual machine running completely in RAM performs better than a virtual machine that must swap some of its memory to disk.
The actual memory size you should give to a virtual machine depends on a few practical considerations:
Note: You cannot allocate more than 2 GB of memory to a virtual machine when the virtual machine's files are stored on a host file system that does not support files greater than 2 GB — for example, FAT.
Vmware Slot Size
The total amount of memory you assign to all virtual machines running on a single host may not exceed 4 GB.