how many vms can i run?

[ranjitcool]

Hey Guys,

We have a quad dual core (8 cpus) and 16gb of ram, considering unlimited disk space, how many vms can i run.

I know it depends on the types of vm and its anticipated load but when my boss asks me i gave him a guesstimate of 25 considering we run light weight vm's.

Another engg in my company thinks that 8 cpu's means only 4 to 5 vms, i think thats wrong, because of SMP.

Please explain and assist

Thanks

May be we all live virtual lives..

[Troy_Clavell]

a good rule of thumb is 4 - 8 VM's per core.

[vmroyale]

Hello.

Unless your memory requirements are very very low, it looks like your available memory will answer this for you.

Good Luck!

[weinstein5]

As Troy pointed out the rule of thumb is 4-8 per core which is a good benchmark for ESX 3.5 - with the improved performance of vSphere you could even narrow that down to 6-8 per core,

With 16 GB you will wun out of memory before you run out CPU resources

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[Rob_Bohmann1]

Sorry but .... It depends... on the workload of your vms and how you configure them. Are your apps cpu or memory intensive or comatose? If disk space is not a bottleneck, then most people run out of memory before CPU with a host configuration of 2GB/core. You will get some memory sharing and ballooning benefits, so say you config your VMs with 1GB of memory each, most with the same OS, I would guess between 15-25 if they are all not busy at the same times and since your characterize them as lightweight. Thats my WAG for the day....

[ranjitcool]

Thanks a lot for the reply guys!!

Off topic, I need a software that i can use to draw network diagrams using vmware and all, you know what I mean.

Can you suggest some so I can draw the topology and get your advices.

Thanks

RJ

May be we all live virtual lives..

[Troy_Clavell]

Use Visio. You can get stencils for free, such as http://www.veeam.com/vmware-esx-stencils.html

[azn2kew]

As Troy mentioned, using MS Visio and specific vSphere stencils here and drag and drop to design your layout. www.hypervizor.com has pretty good vSphere & LM network diagram you can relay to and start from there. I think he did a great job with the diagrams.

If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!

Regards,

Stefan Nguyen

VMware vExpert 2009

iGeek Systems Inc.

VMware, Citrix, Microsoft Consultant

[Troy_Clavell]

I found this tonight while poking around... Great Resource

it''s also linked in the below thread as well

http://communities.vmware.com/thread/226812

[AntonVZhbankov]

Quad dualcore equals dual quadcore, and my dual quadcores runs up to 18 VMs per host with 15% average CPU load.

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VMware vExpert '2009

http://blog.vadmin.ru

[AntonVZhbankov]

Brian, it depends. Tasks divide into cpu-bound and memory-bound, so you are referring to memory-bound tasks, which consumes memory but require a little CPU power. 8 cores can be easily eaten up by just a 3 or 4 VMs running intensive calculations and with light requirements to memory.

---

VMware vExpert '2009

http://blog.vadmin.ru

[bulletprooffool]

What OS are you running on the VMs, how many vCPUs per VM, how hard are you pallnning on running them?

I think 25 light weight VMs could be a reasonable estimate.

If you have a budgetfor this work, you could get in a 3rd party tool to monitor 'typical' vm candidates and draw a baseline.

[vmroyale]

Anton, I agree. I was generalizing, and probably should have defaulted to my typical answer for these types of questions which is to measure and size.

No measure and size = generalize

[ranjitcool]

Thanks for the reply guys,

With all due respect I feel that guy at work has wrong info, each time he claims (with a cool attitude) that a dual quad core cannot run more than 4 vms!!!

All your answers were reassuring and I was sure of it.

The vms will be a mix, example linux and windows. They will only be light weight vms and I don't foresee heavy ones. The only Heavy vm would be a sharepoint server and none apart from that.

RJ

May be we all live virtual lives..

[azn2kew]

Your co-worker might be right if you have really high load SQL, Oracle, Exchange boxes, that you may have to limit to 4 VMs per core or even less if needed just to protect the systems from running smoothly. It's pretty common sense how much workload you can run on a host, the best way is to ACTUALLY perform a real test!

If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!

Regards,

Stefan Nguyen

VMware vExpert 2009

iGeek Systems Inc.

VMware, Citrix, Microsoft Consultant