HariRajan
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can you please tell me how app volume agent works ? or more specifically what is happening in the backend while doing the poweroff / poweron and assigning a new appstack in a view machine without NIC card

Reason I'm asking this is , I was doing some testing with appvolume , I have removed the NIC card of the VDI machine , my understanding was agent is communicating over the VM network to app volume manager all the time (TCP 80 /443) but interestingly once I remove the NIC card app-stacks are still assigned to the machine.

Then I thought of powering off & powering on the machine with NIC card removed and to observe the behavior  ,after a power off app-stacks are removing and when I do the power on appastacks are attaching.


Then I thought of assigning a new app-stack to this machine which don't have an NIC card  ,that is also working fine  as it is attached.

I can guess something here but do you have any insights to this ?! . I'm curious to know what are the back end operation happening during poweroff , poweron , attaching  new appstack and detaching the existing appstack ?.

Thanks & Regards in Plenteous . Hari Rajan
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HariRajan
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Please help me to understand this

Thanks & Regards in Plenteous . Hari Rajan
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Jason_Marshall
VMware Employee
VMware Employee

Does the attached help?

Not sure what you mean without a NIC. We would attempt to communicate with the Manager but it should fail and you would get an error 400 Virtualization disabled in the agent machine. If you are not then there must still be some communication between the Manager and Agent.

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HariRajan
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Hi Jason,

My understanding was app-volume agent in each VDI machine  is communicating to app volume manager for doing the checkin and checkout with app volume manager , but I have removed the Network Interface Card card of the VDI machine and powered off / ON the machine, Surprisingly AppStack’s are detached as usual and attached while it is powering on. My question here is , Since there is no  VM network from VDI machine to appvolume manager , how the disks are detaching and attaching while I am doing the  power off and power on

Thanks & Regards in Plenteous . Hari Rajan
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Jason_Marshall
VMware Employee
VMware Employee

I don't know because the very first thing the agent does on a power up is to get a license from the Manager. If there is no communication with Manager you will get an 400 error that virtualization is disabled. It does this check each and every time. if you look at the Manager logs you will see when the agent checks in during a startup. My guess is there is still some network somewhere allowing this to happen.

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HariRajan
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Hi Jason ,

Is this behavior because of appvolume broker agent in horizon view ?

Thanks & Regards in Plenteous . Hari Rajan
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hockeyguyin714
VMware Employee
VMware Employee

If the NIC was truly disabled View would also be unaware of it powering on and would have no communication to the VM to report via the View Broker Integration Service.  If View is aware the desktop is powered up there is a NIC for communication.

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HariRajan
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I will do the lab once more and will post you the update .

Thanks & Regards in Plenteous . Hari Rajan
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HariRajan
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I have only tested app-stack and writable with machine assignment and I am not sure what will be the behavior with user assignment.

With respect to app stack and writable behavior with machine assignment. please find the observations.


I am confirming the app volume agent and network behavior here , I have done extensive testing to prove that network will not effect the app stack and writable operations (only machine assignment tested & I hope user assignment will also have same behavior) , Only thing is that as like normal operations users cannot connect / take remote of the VDI machine . I have done all my testing by  opening the vSphere console.  

App Volume agent  having two duties 

1. For creating the provisioning machine and appstack .

2.Agent that runs on a users virtual machine as a service.  It is responsible for handling the filter driver which looks after application calls and redirects to the AppStack and writeable volumes VMDK’s.


I mean to say that using vsphere API it is communicating to app-volume manager . if you power-off a VDI VM  which don't have network, as like normal behavior the writable / appstacks will be detached and same you can see as "detached'  in the appvolume manager , while you powering the on the VM , app stack and writable assign back to the machine even-though it doesn't have a network to communicate to app-volume manager,

If you notice, while powering on a VDI machine,  after the BIOS operation (POST) you can see that appstack and writable are attached  to the VM .  It is because vsphere API calls.  This phase as you know the machine is not boot to the OS as well , it is just completed the POST .


Since app-volume agent service running on the VDI machine , if you open the vsphere console you can see that writable are working fine as it will redirect the files Also app-stacks are working fine as expected. but if you stop the appvolume agent service  in the VDI machine you will experience issues and it will not work .


In a real time scenario , One of the VDI machine lost the network connectivity and user is running a critical read and write operations . Are you foreseeing any data loss  and appstack and writable will be detached ?.   In my observation VDI machine will be intact if VDI loses network connectivity and appstack and writables will still assigned to the machine. 


But If appvolume agent freezes or stop , immediately appstack and writables will be detached , in summary if we lose network , still appstack and writable will be functional.

Thanks & Regards in Plenteous . Hari Rajan