Q:

What happens when a new forest is attached to a DB in a clustering environment?

Let's say I have a medium size clustering environment with 2 E-nodes and 10 D-nodes. A new forest is being introduced and attached to one of the D-nodes. What will happen afterwards ?

A:

With default configuration, the rebalancer would get triggered. Most commonly used policy would be Bucket Assignment policy. It would recognize a new forest was added, recalculate bucket distribution, and initiate migration of documents in buckets that were relocated elsewhere.
I'd recommend reading the Database Rebalancing section of the Admin guide:
http://docs.marklogic.com/guide/admin/database-rebalancing
HTH!

