Home > VMware > Be-Aware of VM Sleep mode when enabling VM Monitoring in HA/DRS Cluster

Be-Aware of VM Sleep mode when enabling VM Monitoring in HA/DRS Cluster

We had a freaky issue with one of the Windows VM wherein it was getting restarted frequently. The VM was part of VMware HA Cluster which had VM and Application monitoring enabled. Windows Event Viewer was reporting unexpected Shut down and there were no Windows Memory dump files that was created within Windows which kind of confirmed that the issue was not caused by Windows or any of its application. This could not have been due to hardware issues since other VMs running on the Cluster was running fine without any issues.

For those who do not know what VM Monitoring is ,

When VM monitoring is enabled in a VMware HA Cluster , VMware HA monitors whether virtual machines are available. VMware HA uses the heartbeat information that VMware Tools captures to determine virtual machine availability.VMware Tools sends a heartbeat every second. Virtual Machine Failure Monitoring checks for a heartbeat every 20 seconds. If heartbeats have not been received within a specified (user‐configurable) time interval, Virtual Machine Failure Monitoring declares that virtual machine as failed and resets the virtual machine.

Scanning through the Virtual Center Tasks and Events of the VM , Found that that VM has been restarted by VMware HA and scrolling further showed that VM had entered sleep mode .

Since VM monitoring was enabled , heart beat communication between the VMware VM and host would have got stopped the moment the VM entered sleep mode and hence VMware HA would have restarted the VM thinking that VM is not responding. Good thing about VMware HA is that all events are recorded in Virtual Center and also the fact that it takes and saves a screenshot of the state of the VM  before restart in the Virtual Machine folder.

While I completely agree that VMware HA had to restart the VM since the heartbeat between the host and VM had stopped by the Virtual Machine entering standby mode , Can it be not intelligent enough to avoid restart of VM in these scenario’s since Virtual Center events indicate that VC is aware of the VM entering sleep mode.Test / Development Virtual Machine’s can have power mode configured in them to enter sleep mode when not in use so as to free idle CPU/Memory resources.The only alternate way is to have these VMs excluded from VM monitoring or have sleep mode disabled inside the VM.

Categories: VMware Tags: ,
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  1. September 12, 2012 at 4:30 pm

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