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Bryan Hall's avatar
Bryan Hall
Brass Contributor
Jun 06, 2018

Azure Site Recovery failover/failback with in-guest iSCSI?

What is the behavior of ASR-protected VMs (VMware) with in-guest iSCSI disks?  In this scenario, ASR would be used for DR, not migration (yet).   I understand that protection of such disks result i...
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Bryan Hall's avatar
Bryan Hall
Brass Contributor
Jun 13, 2018

To fail back to on-premises, a method that seems to work in a simple lab environment -- although not ideal -- is:

  1. Delete the source VM (maybe unregistering the VM will work, but I didn't try that).
  2. Re-protect the Azure VM.  (it still needs to be be registered with ASR.)
    • The Config Server/Master Target Server will create a new VM and replicate the disks, including the VHD that had been converted from iSCSI (on the failover to Azure).
  3. After protection has completed full synchronization, fail back to on-premises.

The new VM will be created in ESX with the hostname of the VM.  In my test, the VMDK (of the iSCSI disk) will be mounted, while the iSCSI target's volume was offline, even though there was connectivity to the target.  Aside from choosing the Master Target server, VCenter and 

 

The iSCSI volume can then be mounted, and the data copied from the VMDK to the iSCSI volume, if needed.  Alternatively, keep it as a VMDK.

 

This definitely isn't ideal, as it makes the failback process much more difficult since enough space for the iSCSI disk is now needed on the VMFS datastore, and the entire VM needs to be fully replicated back to on-premises.  However, it does still serve its purpose by providing simple disaster recovery to Azure (it's just a little harder to get it back on-prem).

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