No need for that; but you will required to redeploy them from the
new
engine to update their configuration.
so I keep the old engine running while deploying the new engine on a different
storage? Curious.
I don't understand what "redeploy them [the old engine hosts] from
the new engine to update their configuration" means.
In fact the current engine incarnation is running on an old cluster, that
has no access to the new storage (the cluster is to go away).
The engine is also managing the new cluster to which we want to move the engine.
The engine is the only piece that keeps us from shutting down the old cluster.
That's the motivation for restoring the engine on the new cluster.