A VM that Azure Site Recovery helps protect goes into a resynchronization state

Applies to: Microsoft System Center 2012 R2 Virtual Machine Manager


A virtual machine (VM) that Microsoft Azure Site Recovery (ASR) helps protect in a Hyper-V to Azure scenario may repeatedly go into a resynchronization state. You cannot manually resynchronize, and you may receive the following error message for the replication health of the VM:

Replication State: Resynchronization required
Replication Mode: Primary
Current Replica Server: Microsoft Azure
Replication Health: Critical
Resynchronization is required for the machine X. Resume replication to start resynchronization.
Successful replication cycles: 0 out of Y (0%). More than 20% of replication cycles have been missed for virtual machine X.

 In the error message, the placeholder X represents the name of the VM, and the placeholder Y represents the number of attempts.

You may also see events logged that resemble the following:


This issue can occur if the data disk size of the protected VM is greater than or equal to 1 terabyte (TB). 


The maximum disk size that is supported for data disks in Azure is currently 1 TB. To work around this issue, reduce the hard disk to less than 1 TB. For more information, see the following article: