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Memory Usage in VMware ESXi

Ok Windows Server 2003 Standard in a 32-bit environment only uses 4GB of memory. If I have a server with 16GB of memory and ESXi installed on it then can I have 4 different Server 2003 VM each with 4GB? Like does ESXi recognize all of it and share it out correctly in a 32-bit environment?

I am new to virtualization and just trying to get a better understanding of it.

Thanks in advance for your help.
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kserritt
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kserritt
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larstrCommented:
If you install 4 servers you will be able to give each of them 4GB. Be however aware that Windows 2003 Standard can only see 3GB unless you boot with the PAE parameter. Also see here for more information:
http://support.microsoft.com/kb/283037/
http://support.microsoft.com/kb/291988/

Since you'll be using all memory you will be overcomimitting memory (ESX still needs some, and you also have some overhead per VM). But memory sharing will over some time help you out since you're running the same OS on all of your VMs.

A 4GB 1 vcpu 32 bit guest will have 136.5MB overhead. If you start all your VMs in a very short period you will because of this see both ballooning and swapping until enough memory pages between the virtual machines have been identified and shared. Because of this your virtual machines might run a bit slowly until this point.

For better understanding on how ESX is dealing with memory and resources please see:
http://www.vmware.com/pdf/usenix_resource_mgmt.pdf
http://www.vmware.com/pdf/vi3_35/esx_3/r35/vi3_35_25_resource_mgmt.pdf

Lars
vkktreeesxboot.jpg
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kserrittAuthor Commented:
Thank you very much for the information.
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