Virtual server - lessons learnt about vCPU
Fredrik Malmborg June 18 2012 06:29:39
I learnt something interesting about vCPU (Virtual Central Processing Unit) on virtual servers. I trust the source of the information but if anybody have more input about this I would be glad to know.What I learnt is that when configuring a virtual server for Lotus Domino or other server application it is of no much use to assign more than 2 vCPUs. That makes me even more confident that it is a very good idea to keep heavily used Domino servers away from virtual machines.
Another interesting fact when considering going virtual is that when you ask for 2 vCPUs, it does not promise you anything about the perfomance of these vCPUs. Your vCPU depends on the amount of other virtual servers on the hardware. There can be more vCPUs assigned than available CPUs on the motherboard.
Also interesting to read that adding more RAM to a virtual machine not neccessarily gives better performance. And it looks like it prefers "even" allocations like 512, 1024 or 2048.
I think BrianEh gives a nice overview here http://social.technet.microsoft.com/forums/en-us/virtualmachinemanager/thread/97573AEB-6DAA-4F98-8D92-BECDBA65A8A3
I do like the concept with movable images of full system with OS and everything installed and configured. There are also some nice features regarding backup and restore.
I imagined that by virtualizing the servers it would be easier to assign more memory and processor resources as the load increase. But it seems like it is not that simple.
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