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Virtual machines not balanced between ESXi Servers

Posted on 2014-07-26
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Last Modified: 2014-07-28
I have 2 ESXi servers , I have created a shared storage, then 2 Windows 7 machines.
For some reason in Vsphere Client under the Summary tab of each Windows 7 VM, I see the Host is the same.
Now I can power On only one Windows 7. If I try to power them both, I get insufficient memory on the Host.

Though both ESXi servers are under the cluster, and I enable VMHA and DRS

Any help will be very much appreciated

Thanks
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Question by:jskfan
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by:Andrew Hancock (VMware vExpert / EE MVE)
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How much memory is in the Host ?

and how much memory is assigned to the VMs ?

Is the total memory assigned to each VM, exceed the memory in the host ?

Do you have VMware HA enabled, and VMware DRS set to FULLY Automatic.

So when you power-on the VMs, it allocates the VM to a host automatically with enough resources.

However, with only two hosts, and VMware HA, an Admission Rule, may state you do not have enough resources, because if a HOST failed, you may not have enough resources to start ALL VMs on the remaining host.

You can disable this admission rule in VMware HA, BUT remember if you do this, and try to start two VMs with 16GB (32GB) total, on a host with 16GB, you will over subscribe the host, and it will run very slowly, as it starts to swap 16GB to disk!
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by:jskfan
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Each ESXi server has 4096 MB (4GB) of RAM
Each windows 7 just 1 GB of RAM

VMHA and DRS are enabled set to Fully automated (it was by default)
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by:paulsolov
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Keep in mind that each ESXi hosts needs to have at least 2GB RAM to run.  After the ESXi hosts powers on you may not have enough memory to run two 1GB nodes, it's 1GB RAM on each VM but there's also overhead.  I would at least double the memory to 8GB RAM if you want to do this

      
from vmware documentation:

ESXi requires a minimum of 2GB of physical RAM. VMware recommends 8GB of RAM to take full advantage of ESXi features and run virtual machines in typical production environments.
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by:Andrew Hancock (VMware vExpert / EE MVE)
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It's very close, 2 x 1GB for VMs, and 2GB for Hypervisor, and only 4GB in Hosts!

Is this a virtual lab, increase the RAM in the hosts!

Most Labs have a minimum of 8GB and most have 16GB or 32GB.
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by:jskfan
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4GB RAM on each host, I have 2 hosts which means 8GB
I have 2 windows VMs each with 1GB, so total 2GB

I do not see the reason why 2 VMs cannot run separately in 2 ESXi servers

You would think they both can run even  in a sing ESX host since it has 4GB...

I do not know how to configure each VM to run in separate ESX host
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by:jskfan
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I am bumping each host to 6GB of RAM and see
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by:jskfan
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Well, after I bumped each Host to 6GB of RAM, I managed to power both Windows 7 VM, however they both run one ESXi host.
Though both VMs are installed on a shared storage
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by:paulsolov
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Migrate each VM to a different ESXi host and give it a try.
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by:jskfan
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I tried to manually migrate a VM  it opens up "Select Migration type" window, everything grayed out except for "Change Datastore"
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by:paulsolov
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To have the capability to perform vmotion between hosts you need to have a vmotion vmkernel port defined.  If you're seeing only change datastore option you have not configured any vmkernel ports for vmotion.
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by:jskfan
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I managed to enable Vmotion on both Hosts now...
Though before I enabled Vmotion, I restarted the Management agents on both ESXi hosts, I guess that made each Windows 7 VM to run on separate ESXi host..
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Andrew Hancock (VMware vExpert / EE MVE) earned 251 total points
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without vMotion working and being enabled, it cannot transfer a Live Machine via vMotion - that functionality would have been broken!

VMware HA does not rely on vMotion.

It restarts VMs on other available hosts.
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by:gheist
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And given limitations outlined above actually you have <2GB space on each ESXi, so you cannot have HA availability control or even any successful HA recovery in your cluster.
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by:jskfan
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Thank you Guys!
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by:gheist
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Cheapest option is to max out RAM (also by means of long-term electricity consumption)
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