I was looking yesterday at post from Matt McSpirit regarding the Cluster Limits of Hyper-V. I started to look at how this would compare to vSphere.
I do not want to go into who can cram more VM's into a cluster VMware / Hyper-V? I did notice something that I realized - I think I should point out.
Take the following Scenario.
Now you want to add another Host to your cluster.
On pg. 7 of The Configuration Maximums for vSphere 4.0 and vSphere 4.0 Update 1 you will see that when adding the 9th host - the number of VM's per host is limited to 40.
So therefore the scenario will change to this:
In thinking that you can increase your capacity in your Cluster but adding another host - you just reduced the number of VM's that can run in your cluster 280!! In order to get back to the same amount of VM's you were previously running - will need another 7 additional hosts
As always my advice is - read the documentation and research the implications of your actions will be.
6 comments:
The max is not 100 but 160! (page 7: http://www.vmware.com/pdf/vsphere4/r40/vsp_40_config_max.pdf)
I guess the real questions are:
- what is the anticipated consolidation ratio?
- how many eggs do you want to have in a basket?
- what is the risk you are willing to take?
Thanks for pointing that out Duncan - I will update the table.
All of the questions you asked are extremely relevant and should be taken into account, regardless.
Another simple solution would be to split environment to two clusters and still have max. 160 VM's per host.
Just my 2 cents.
Wouldn't you be reducing capacity only if you were already running more than 40 VMs per host? Sure the max number is lower, but the effective number depends on the VM sizing and actual resource usage.
Thanks que.
I agree the sizing will have to be done in advance - and should always be the sterring factor for your decisions.
That is precisely the point :)
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