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trojan81 asked
Hi Experts,

I'm not a server guy. This is a question about ESX host and VMs.

Let's say an ESX HOST HAS:

Processor:  2 x Quad-Core Intel Xeon, 2333 MHz
HD: 500GB

If you create a VM and give it 2GB of RAM and 2ghz processor and 200GB HD, does that subtract from the  ESX HOST?
So that will leave the ESX HOST with less processor, 2GB ram, and 300HD space?
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Pete LongTechnical Consultant
Distinguished Expert 2019
>>If you create a VM and give it 2GB of RAM and 2ghz processor and 200GB HD, does that subtract from the  ESX HOST?

No, memory, can be over commited, HDD can be thin provisioned, and virtual processors dont really relate to real processors.

That depends:

ESX host itself does not need memory or CPU by itself, only other VMs running on the host may need the recources.

RAM gets assigned imidiatelly. In your example, before you turn on the VM the host will use lets say 50mb RAM. After you turn on the VM the host will use 2gb and 50mb of the availible RAM to the host.

CPU gets assigned as neded. That is, if the VM uses one core to 100% that will be use by the host and means that the other VMs residing on the host will have to share

HDD space depeds on the mode of alocation you use. You can use dynamic (space gets assigned as its filled, but the VM sees full 200GB availible) That means that on the host the actual virtual HDD file itself will only take up as much as it has data in it.

Or you use static allocation, meaning all 200GB will be alocated to the VM right away.

Just to add, yes, same thing as with a dynamic HDD allocation can be done with memory, but the guest OS on the VM has to support that.

And about the CPUs: cirtual CPUs dont have to match with real CPUs. You can assign 50% of a single core on the host to a VM.

VM uses that to 100%, but only 50% of that core will be used on the host, since that is how much the VM gets from the host.
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Expert of the Year 2017
In theory yes, storage will be reduced, although you could use Thin Storage, 2GB would be reduced from the servers main pool, but could be re-allocated, VMs only use Memory they require, so even if you add 2GB, only 1GB maybe active.


Thanks experts!

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