The short answer is yes, the VCL will prevent over-provisioning of the VM hosts.
... The long answer is when you configure the RAM on a certain computer, that value will be the maximum RAM given to the image when it starts up. The actual amount of RAM assigned to a VM is controlled by the setting on the image. So, for example, if nodes 1-10 each have a RAM setting of 8GB, but all are running 4GB images then they will "consume" only 40 GB of the available RAM on the host. You will also notice that each VM host has a total amount of RAM allocated to it, so, if your host has 80 GB of total RAM, then the VCL will only allow 10 8GB images or 20 4GB images -- any combination of images that fit into that total value. That said, in my experience working with VMware, it is also possible to oversubscribe RAM. That is, if a given VM is configured to use 4GB of RAM, it most likely is only using a small portion of that. So your 10 4GB images may *actually* be using only 8GB of physical RAM. The difference between allocated RAM usage and actual RAM usage will depend entirely on the types of applications being used. In our system, I oversubscribe the RAM on our host clusters by about 25% (not including the RAM used by VMware ~250MB/VM), and I have yet to see the actual RAM usage rise to a level that would even begin to concern me. In terms of where to set those values, I simply monitored the VM host performance data and incrementally increased the number of VMs to a level where I felt I was maximizing the CPU - RAM - I/O resource performance over the largest number of VMs. I hope that helps. Best regards, Aaron -- Aaron Coburn Systems Administrator and Programmer Academic Technology Services, Amherst College [email protected]<mailto:[email protected]> On Feb 12, 2013, at 9:35 AM, "Basilio, Norvin" <[email protected]<mailto:[email protected]>> wrote: Hello, I am curious on how others are configuring their VM computers. Right now I have configured groups of computers with ram configurations of 1GB, 2GB, 4GB, and 8GB. I've also grouped images the same way and mapped them to the corresponding computer groups. My problem with this method is that I have obviously limited the total numbers as it will not load 8GB vm computers with a 1GB image. I would like to know if I configure the the VM computers all as 8GB VM's will the vcl code stop any over provisioning the esxi hosts? Norvin Basilio Email: [email protected]<mailto:[email protected]>
