A common task for administrators is to move data from one location to another. In the
most abstract sense, this problem encompasses a large number of use cases, from
replicating data between servers to keeping user data on laptops in sync with servers.
There are many external tools available to do this, but the ZFSSA has two integrated
solutions for migrating data that addresses the most common use cases. The first, Chapter 13, Replication, is intended for replicating data between one
or more ZFSSAs, and is covered separately. The second, shadow migration, is described
Shadow migration is a process for migrating data from external NAS sources with the
intent of replacing or decommissioning the original once the migration is complete. This
is most often used when introducing a new ZFSSA into an existing environment in order to
take over file sharing duties of another server, but a number of other novel uses are
possible, outlined below.