With Exchange 2013 Cumulative Update 1, administrators will notice that every time a new database is added, they are prompted to restart the Information Store service. Although this was also true in Exchange 2013 RTM, the difference was that before administrators did not receive this restart warning.
As we saw previously, Exchange 2013 introduced the new Managed Store, which uses a different memory management model than previous editions of Exchange. With a Store Worker Process for each active and passive database present on a server, it is now required to restart the Information Store service because the Store only determines the amount of memory that it will use to manage each database when it starts (which happens when the server starts or when the Information Store service is restarted).
In previous editions, Exchange typically seizes as much memory as it is available on a server and uses that memory to cache Store data. In Exchange 2013 this approach was revised and it now calculates how much memory it should use and makes it available to worker processes (obviously active databases are assigned more memory than passive databases). However, this new memory management approach depends on knowing how many worker processes are in use. When databases are added from a server, the Store does not re-calculate the amount of RAM for each worker process dynamically. This does not mean that you cannot mount the new database – it means caching will not be as efficient as it should be until the next time the Store process restarts and memory use is adjusted.
This might be seen as a big drawback of Exchange 2013, and it might even change in the future, but adding or removing databases should not happen that often, so the impact should not be that massive.