The migration of a vTree is restricted when it contains more than one volume and the destination storage pool has a different data layout (e.g., migrating from a Fine Granularity to a Medium Granularity pool). This limitation exists because the system cannot perform the complex data re-striping required for multiple volumes simultaneously while guaranteeing the point-in-time consistency of the vTree snapshot. However, migrating a vTree with a single volume to a pool with a different data layout is a supported operation.

1. Dell PowerFlex Administration Guide (Version 4.x): In the chapter "Volumes and Snapshots

" the section "Migrate V-Trees" explicitly states the restriction: "A V-Tree that contains more than one volume cannot be migrated to a Storage Pool with a different data layout." This confirms that the combination of multiple volumes and differing data layouts is the specific constraint.