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I normally setup larger clusters than a 2-node cluster with shared storage, but we have built a cluster specifically for hardware based GPU's for a few VMs and thus new hardware and just a 2-node cluster with backend shared SAN storage.

The 2 hosts have 384GB RAM and dual 10 core procs.

Total VM count = 12 with total vCPU assigned equaling 36 Total VM cpu utilization is around 5% on each, and 35% ram on each.

My question is:

Is there a preference or best practice on the host admission policy? Right now I have it set to "cluster tolerates 1 host failure" but typically I would set cpu/ram percentages with larger clusters. However, when I do this regardless of setting (25/25, 15/15, 50/50) I end up with VM's showing "unprotected". Setting it back to a single host failure sets them all back to "protected".

Are there certain settings for HA and DRS to take into consideration when only dealing with a 2 host cluster?

The cluster is currently running on 5.1 but I don't think the options have changed since.

ewwhite
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TheCleaner
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1 Answers1

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See: Should VMware HA Admission Control be enabled for small (2/3-host) clusters?

Don't enable admission control for a 2-host environment. Unless you're dealing with well-calculated or custom slot sizes or VMs or resource pools with reservations, there's no benefit to doing this.

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ewwhite
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  • Thank you. I don't know how I missed that one in the search, but after reading your discussion there it makes sense. I'll go with that! – TheCleaner Jan 25 '16 at 19:00
  • I think VMware provides bad information about this stuff. The defaults are terrible and understanding resource math is tough. – ewwhite Jan 25 '16 at 19:01
  • @TheCleaner: You can view the "calculated" slot size by clicking `Advanced Runtime Info` on the cluster summary page. As an aside, Hyper-V uses only allocated RAM as the slot size determinant. – joeqwerty Jan 25 '16 at 21:07