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We're currently in the process of setting up a server here in a research environment. It would be ideal to use VMware ESXi, but (and I apologise if I get this completely wrong, I'm somewhat new to this) that needs to be installed on the machine initially instead of an OS correct? and then operating systems are installed as virtual machines? However the free version of it isn't suitable for us, the limitations on RAM would make the money we spent on the server redundant. We also looked at Cirtix XenServer free, which apparently has an upper RAM limit of 256GB, which again isn't enough (We have 512GB of RAM, over 4 CPUs which have 16 cores each). Now am I correct in assuming these virtualisation tools cannot be installed over an OS? Because it would be useful to install some linux based operating system on the server, which would have access to the full machine which we can log onto when running particularly intensive programs, but also have a number of virtual machines set up for other people to log into?

Is this possible?

Thanks in advance!

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Just install CentOS with KVM as virt technology. That way, single VMs are limited to 32TB RAM each, while the base OS is limited only by what Linux can do. And next time, consider license costs up front when planning to buy such a machine. – Sven Aug 8 '13 at 14:32
What specific CPU models do you have? – ewwhite Aug 8 '13 at 17:07
As @SvW mentions, KVM will do what you want. Red Hat has some great documentation on setting this up. The same documentation will work on CentOS. – Aaron Copley Aug 8 '13 at 17:25
Of course you are not limited to CentOS with KVM. Many distributions are suitable as KVM hosts like ubunut or debain (if you like them more) – Christopher Perrin Aug 8 '13 at 20:29
up vote 8 down vote accepted

A licensed copy of VMware ESXi, including vCenter (the Essentials Pack) is $500-$600US. There's no RAM limit, and it could accommodate up to three hosts.

Given the specifications of your physical hardware, the cost of obtaining the right VMware licensing is negligible.

Do the right thing!!

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Essentials is limited to 2 CPUs per host. OP has ("over"?) 4. – ThatGraemeGuy Aug 8 '13 at 14:56
You can divide the license however you wish. Essentials provides 6 physical CPU socket's worth of licensing. Four of them can be applied to one four-socket host, or you can use six single-socket hosts. It all works. – ewwhite Aug 8 '13 at 14:58
Edit. Nevermind! I just read the other comments. This looks great! Can I ask though, why pick VMware over oracle, which is completely free with no restrictions, and according to the oracle website is better at everything?… – TheFoxx Aug 8 '13 at 14:58
@TheFoxx The licenses can be split and divided. You have a maximum of three hosts that can be managed under that license. That could be a quad-socket machine and two single-socket systems, or three dual-sockets systems. This is documented and supported, as I do the same on some systems. – ewwhite Aug 8 '13 at 15:03
@TheFoxx Marketshare. I don't know anyone who uses Oracle Virtualization. I know lots of organizations who use VMware. Mindshare and marketshare count for something. – ewwhite Aug 8 '13 at 15:49

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