arcserve-KB : UDP || UDP Agentless | VM guests need disk consolidation after switch to agentless backups

Last Update: 2018-03-27 15:36:45 UTC
Randomly for few virtual machines an alert is received stating that snapshot consolidation needs to performed . When they try a manual consolidation it fails with the message:
An error occurred while consolidating disks: msg.snapshot.error-FAILED.The maximum consolidate retries was exceeded for scsi0:1.

Vcenter 5.5.0 build 2442329
esxi 5.5.0 1892795
Virtual Machines protected using UDP's Host-Based Agentless task. 

The problem is caused due to a know behaviour in ESXi 5.5.x,
This message is reported in ESXi 5.5.x if the virtual machine is powered on and the asynchronous consolidation fails after 10 iterations. An additional iteration is performed if the estimated stun time is over 12 seconds. This occurs when the virtual machine generates data faster than the consolidated rate.

Please follow the steps listed under the Resolution Section of the VMware KB -


To resolve this issue, turn off the snapshots consolidation enhancement in ESXi 5.5, by setting the snapshot.asyncConsolidate.forceSync to TRUE:

Note: If the parameter is set to true, the virtual machine is stunned for long time to perform the snapshot consolidation, and it may not respond to ping during the consolidation.
  1. Shut down the virtual machine.
  2. Right-click the virtual machine and click Edit settings.
  3. Click the Options tab.
  4. Under Advanced, right-click General, click Configuration Parameters and then click Add Row.
  5. In the left pane, add this parameter:
  6. In the right pane, add this value:
  7. Click OK to save the changes.
  8. Power on the virtual machine.
To set the parameter snapshot.asyncConsolidate.forceSync to TRUE without shutting down the virtual machine, run this PowerCLI command:

get-vm virtual_machine_name | New-AdvancedSetting -Name snapshot.asyncConsolidate.forceSync -Value TRUE -Confirm:$False

Alternatively, you can use one of these workarounds:
  • When the virtual machine is under heavy IO load, retry snapshot consolidation at a time when the virtual machine is issuing less IO.
  • Increase the time limit on the snapshots consolidation by changing the snapshot.maxConsolidateTime parameter in the virtual machine.
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