seniord
Enthusiast
Enthusiast

Virtual Machine Heartbeat - How does it communicate with VC?

Hi all,

I am hoping to get some detailed information on how the Virtual Machine Heartbeat communication work. I understand that you must install VMware Tools in order for the Virtual Machine heartbeart to be active. I also understand that VMware Tools reports the heartbeat to VirtualCenter.

What I would like to understand is how does VirtualCenter receive the heartbeat from VMware Tools? Does VMware Tools use the VM network interface to send the heartbeat? Or does VMware Tools report to the ESX host and then VirtualCenter gets the information from the host?

Any infomation would be helpful in order to resolve an ongoing debate!

Thanks, DK.

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9 Replies
kooltechies
Expert
Expert

Hi,

This is how I think it works. VM Heartbeat mechanism does not require a network card , as it is carried out by vmware tools. VMware tools report the heartbeat every second which is then trapped by the ESX servers Virtual machine failure monitoring mechanism. When VC needs this information it will ask the vpxa process and then vpxa will request hostd for the information.

vpxa is the VC agent and hostd is the ESX agent so VC will have to request ESX server for the information regarding the VM heartbeat.

Just my 2cents.

Thanks,

Samir

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Troy_Clavell
Immortal
Immortal

This guide is useful as well

http://www.vmware.com/pdf/vi3_35_25_vmha.pdf

I don't know whether or not you are looking at this to enable VMM, but I would not, based on this KB

Virtual Machine May unexpectedly reboot when using VMware HA with Virtual Machine Monitoring on ESX ...

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Cooldude09
Commander
Commander

DK, i believe heartbeat has nothing to do with VMware tools, as VM's which dont have vmware tools installed, do work fine in a cluster with HA enabled. I believe it has to do something with ESX VMM driver on which the VM is installed. VMM is nothing but a driver which is a replica of the hardware on which ESX in installed. So heartbeat should be the mechanism for VC to talk to ESX VM's VMM.

Regards

Anil

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seniord
Enthusiast
Enthusiast

Hi Samir,

Thanks for your '2 cents' worth. It does sound like a good explaination of how the heartbeat works. I have found no official documentation from VMware regarding this functionality (except to say that it requires VMware Tools), hence the post.

I am attempting to explain this heartbeat to a customer in order to resolve an unrelated issue so any further confirmation would be appreciated.

Thanks

Daniel.

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seniord
Enthusiast
Enthusiast

Thanks Troy. I have seen this document but unfortunately it does not explain exactly how the heartbeat is communicated from VMware Tools to VirtualCenter. I am not looking to use VM HA but just to understand the heartbeat communication process.

Daniel.

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seniord
Enthusiast
Enthusiast

Anil,

According to all VMware documentation, you must install VMware Tools for the VM heartbeat to be reported correctly to VirtualCenter (see links in previous post). VMs can reside in an ESX HA cluster without the heartbeat activated.

What I am trying to understand is exactly how VMware Tools communicates with VirtualCenter.

Daniel.

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Cooldude09
Commander
Commander

Daniel, apologies to miss out the link, Troy thanks a lot for for the document. Thank you for clarfying the same.

Regards

Anil

Save the planet, Go Green

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seniord
Enthusiast
Enthusiast

Is there anyone else who can confirm what Samir explained about how the VMware Tools heartbeat communicates with VirtualCenter?

Or is there any different opinions?

There are points still to award for further clarification... otherwise they all go to Samir!!

Thanks

Daniel.

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manikandanrvs
Contributor
Contributor

Depends on the vmware tools status we are deciding the virtualmachine's heartbeat status.

Vmware tools having 4 status :

grey -not yet powered on

yellow - vm is powering on

green - vm poweredon and recieving the heart beat

red - invlaid vm or vm crashed .

Vpxa is a agent that keep checking the hostd and sending heart beat status to VC. So the vpxa will inform to VC about the host status not VM status .

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