First you can use snapmirror for volume replication, you have to upgrade the two machines to the appropriate version, you also have to set aside time for planning, choose the right time for data cutover, you need time to remount.
The second method you can use volume movement, will be added to a cluster, the volumes are migrated to A220, you can suspend the migration at any time, until the business is not busy to continue migration, no need to cut the window, automatic completion, the front-end is not aware