Cluster size of 8 is the only size to do
For a large organization that has more than 8 VMware Hosts (nodes) one should only make 8 node clusters for the time being according to the vSphere 4 Config Max doc.
http://www.vmware.com/pdf/vsphere4/r40/vsp_40_config_max.pdf
If you look on page 7 it says “Configurations exceeding 40 VMs per host are limited to cluster size no greater than 8 nodes“.
What that means is to be supported you have the following chart:
8 Nodes x 100 VMs / Node == 800 VMs per cluster max
9 Nodes x 40 VMs / Node == 360 VMs per cluster max
20 Nodes x 40 VMs/ Node == 800 VMs per cluster max
32 Nodes x 40 VMs / Node == 1,280 VMs per clustre max
Now I might not be too smart here some days though I think the math is pretty obvious. Either I do 4 clusters of 8 nodes to give me 3,200 VMs on 32 boxes or I stick them all into one nice big cluster and get 1,280 VMs out of those 32 boxes. Easy math to me.
The question I have out of this is, why do you document it this way? That sure is confusing and I could have easily missed that.
In: Server Virtualization, VMware · Tagged with: cluster, maximums, vSphere4
on 1 June 2009 at 8:14 pm
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http://www.yellow-bricks.com/2009/05/25/max-amount-of-vms-per-host/
on 2 June 2009 at 3:27 am
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Hrm.. didn’t quite beat you to this information Duncan.
on 19 May 2010 at 12:52 pm
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Ian, that all being said. If you are fine with 40 or less VMs per host, there is nothing wrong with a larger cluster is there? Generally, I see 8 or less more for storage limitations (# of LUNs) than for arbitrary software limitations of VMware.
on 19 May 2010 at 8:20 pm
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To my knowledge and testing you should be fine going above an 8 host cluster if you don’t mind having 40 or less VMs per host average. It is all around HA working. I haven’t had an issue with the # of LUNs per cluster (256 max) causing an issue yet. I have a couple clusters currently with 10 hosts and around 400 VMs in the cluster and about 25 or so LUNs. So for me to hit the 256 I’m going to have to really pack in the VMs since there is a 32 Host Cluster limit at this time too.