Faster Shared Nothing Live migration with NetApp Copy Offload

Windows Server 2012 provides us with 2 new options for VM migration –shared nothing live migration and storage live migration. While shared nothing live migration depends on host to host communication on the Ethernet network, storage live migration can be offloaded to the storage subsystem if the storage array using ODX technology. Shared nothing live migration is exciting since VMs across different clusters or standalone systems over the network can be moved. Shared nothing live migration will incorporate the necessary Live Storage Migration if needed to accomplish the task, and will see all of the advantages of the ODX technology in the NetApp target device. In a case where a VM that would take 20-30 min to copy over the network, it could be accelerated to just under 2 minutes (tested with a base W2012 VHDx of 8GB size)

The second migration method is simply a Live Storage Migration, which allows you to move the underlying storage that a VM is using, without moving the VM itself. In many ways this Live Storage Migration is a subset of what is required for a Shared Nothing Live Migration.


Here are the steps


1. First, verify that copy-offload is enabled on the NetApp storage array from a CLI connection.



2. If you wish to monitor Copy-offload activity on the storage system ,login to the diagnostic mode on the storage system and enter the following command -


                    Statistics start –object token_manager –sample_id <sample name>


     *Please be extra cautious while accessing the diagnostics menu*


3. Initiate the shared nothing live migration workflow as usual






4. While copy is in progress login to the storage system and type the following command


                    Statistics show –sample-id <sample name>


This will output the amount of data been copied.




In the above case we see that 1000 ODX tokens are created, and each token is 8MB in size. This implies that the storage system handled

1000 x 8MB token offload requests.