Let’s begin this post with a recap of the Storage vMotion enhancements made in vSphere 5.0. Storage vMotion in vSphere 5.0 enabled the migration of virtual machines with snapshots and also the migration of linked clones. It also introduced a new mirroring architecture which mirrors the changed disk blocks after they have been copied to the destination, i.e. we fork a write to both source and destination using mirror mode. This means migrations can be done in a single copy operation. Mirroring I/O between the source and the destination disks has significant gains when compared to the iterative disk pre-copy changed block tracking (CBT) mechanism in the previous version & means more predictable (and shorter) migration time.