ENeumann
Contributor
Contributor

Memory Overhead Formula

Does anyone know where I can find the formula to calculate the memory overhead a VM has? I know there was one for an older version of VMWare but I've searched the documentation adn I can't seem to find any reference to a formula anymore... I have this handy dandy chart but a lot of my VMs memory sizes aren' on that chart...

Table 9 2. Overhead Memory on Virtual Machines

Virtual CPUs

Memory (MB)

Overhead for 32-bit virtual machine (MB)

Overhead for 64-bit virtual machine (MB)

1

256

79

174

1

512

79

176

1

1024

84

180

1

2048

91

188

1

4096

107

204

1

8192

139

236

1

16384

203

300

2

256

97

288

2

512

101

292

2

1024

101

300

2

2048

125

316

2

4096

157

349

2

8192

221

413

2

16384

349

541

4

256

129

511

4

512

133

515

4

1024

141

523

4

2048

157

540

4

4096

189

572

4

8192

222

605

4

16384

350

734

Your help is much appreciated.

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azn2kew
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You can use this tool to plugin your virtual machine memory requirements and it will generate the results for you at

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Regards,

Stefan Nguyen

VMware vExpert 2009

iGeek Systems Inc.

VMware, Citrix, Microsoft Consultant

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 vExpert, VCP 3 & 4, VSP, VTSP, CCA, CCEA, CCNA, MCSA, EMCSE, EMCISA
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ENeumann
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Yeah, i've seen this page before. That doesn't tell me how much memory to allocate to the VMs for VM Kernel. That's the bit I need to find out so I know how large to make the memory for my VMs. I'm looing for some sort of formula to replace the chart I have above. See, it doesnt have certain memory levels on there and I want to be as exact as possible.

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azn2kew
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Have you read this thread, it has several tools and a formula you can check out http://communities.vmware.com/thread/102973

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

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 vExpert, VCP 3 & 4, VSP, VTSP, CCA, CCEA, CCNA, MCSA, EMCSE, EMCISA
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ENeumann
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I've seen that thread too... It doesn't seem to be what I'm looking for either... I'm trying to find how best to plan for VMs in my enironment. I know how much memory I want to give each Vm, I just nee to plan for the overhead that VMWare tacks on to whatever I have. This chart above is wonderful adn all but I've got servers with 10GB of memory and thats not on the chart... How did VMWare come up with the numbers in this chart? I assumed it was from some formula they devised. Thats what I'm looking for

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azn2kew
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Its hard to come by that's all I can get why don't you try 150MB for the overhead it seems to fit the bill.

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

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 vExpert, VCP 3 & 4, VSP, VTSP, CCA, CCEA, CCNA, MCSA, EMCSE, EMCISA
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ENeumann
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I'm not trying to figure out how much memory to give a VM, I already know that. I'm trying to figure out how much extra memory my VM is going to use thanks to the overhead VMWare has. This is really for planning purposes. I want to know the impact of bringing up a new VM in my environment. That way, I know when to purchase more resources.

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azn2kew
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Isn't it the chart said the over head for 32bit machine for 8GB RAM is 132MB? If you have 10GB RAM machine wouldn't it be good at 150MB for the overhead? If not, good luck finding the right info.

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

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 vExpert, VCP 3 & 4, VSP, VTSP, CCA, CCEA, CCNA, MCSA, EMCSE, EMCISA
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ENeumann
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No, a 64bit machine with 10GB of ram should use between 400 and 600MB of overhead. Thats the problem. I want an exact amount of overhead to plan for whatever level of RAM I have. It seems hopeless though. Maybe I'll just round up to the next level on the chart and plan for the absolute worst 😕

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