akoustic
Contributor
Contributor

65 VMs X 1CPU and 4Gig RAM configuration

Hi all,

Just trying to do some calculations on what kind of resouces I'd need to have 65 VMs running 1 CPU each and 4 Gig RAM per VM. Storage will not be an issue as we have plenty.

We are using HP C-class enclosure with 16 slots. What congfigurations would you recommend?

Thanks,

Kevin

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8 Replies
dquintana
Virtuoso
Virtuoso

Hello akoustic,

How many real memory do think that the vms will use?, 3 GB?

Ing. Diego Quintana - VMware Communities Moderator - Co Founder & CEO at Wetcom Group - vEXPERT From 2010 to 2020- VCP, VSP, VTSP, VAC - Twitter: @daquintana - Blog: http://www.wetcom.com-blog & http://www.diegoquintana.net - Enjoy the vmware communities !!!

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Troy_Clavell
Immortal
Immortal

I guess the right answer is it depends.

....but with out knowing anything sorrounding your enviornment, I would say 8 BL460's with a couple quad cores each, and 64GB of RAM would be very sufficient.

Depending on the guest OS, you may find 4GB RAM to be too much.

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oboloori
Contributor
Contributor

Hi Kevin!

With VMware planning, there are many factors to consider. I'll make a two assumptions to help you start the process.

  1. I'll assume that you have low CPU utilization on all servers. This will allow us to greatly oversubscribe the CPU pool.
  2. My next assumption is that your 65 VMs will be on average using 75% of the RAM that they are assigned. This will allow us to partially oversubscribe the CPU pool.

So, 65 VMs x 4GB RAM x .75 utilization = 195 GB RAM needed in your pool.

You'll need 4 HP BL460 G7 servers with Dual-Quad Core 5600 CPUs and 48GB of RAM (6 x 8GB dimms) giving you a total of 32 CPU cores and 192 GB of RAM. Of course, I would suggest purchasing a 5th server which would give you the redundancy that VMware is built upon.

DCjay
Enthusiast
Enthusiast

Hello,

I suggest troys  suggestion for 8 servers. for best performance, 1:1 cpu is the way  to go.

8 serer with dual quad core cpu will give you a total of 64 cores.

This will also give room for growth.

Jay

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tietzjd25
Enthusiast
Enthusiast

Troy and DC have give the response I would give. OO- Has given very technical minimal build. (Somthing I need keep in mind when take my DCD test) Smiley Happy

I would at least go with 6 servers to keep N+2 Design but 8 host at 64 GIG will keep you at N+2 and no memory overcommit with room to grow.

Can I ask what you are building 65 VM's with that configuration almost seems like a Desktop roll out......... ??

Joe Tietz VCAP-DCD Solutions Architect
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Tigerstolly
Enthusiast
Enthusiast

Can't help thinking that a 1:1 p to v cpu ratio is slightly overkill, based on all the workloads i commonly see.

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oboloori
Contributor
Contributor

I agree with Tiger. We're seeing a 15:1 vCPU ratio on most of our ESXi servers. With all due respect, isn't the whole point of Virtualization to consolidate on hardware? Smiley Happy

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There are 2 answers here.

1.) When you are requesting budget for the kit, you need to request something along the lines of what Troy has said above (1:1 Virtual to Physical CPU), maybe even more.

No doubt, you will not get what you are asking for, but as long as you keep memory high and are not hammering your CPUs, you can get away with FAR less.

2. ) I have sen environments with 30:1 ratios run perfectly, as workload on different VMs was balanced through differently daily and monthly cycles.

In reality though, you could probably have a functioning cluster with half of Troy's design work 100% properly, but you need to remember that once you implement this, the requirements will quickly grow. People quickly realise that VMware is resource on tap and start requesting all sorts of machines.

The advice in the various posts is well worth taking - the only remaining thing I can add is that you always should overspecify your design and if possible have enough resource for at least 1 host in the cluster to go down at any time (but preferably 2)

good luck and please post back with your eventual design.

One day I will virtualise myself . . .