Microsoft Office Tutorials and References
In Depth Information
Third-party migration tools
INSIDE OUT “Migration Performance” white paper
Microsoft has provided an excellent TechNet article about migration performance based
on experience and observations from actual customer migrations to Office 365. The
“Migration Performance” white paper is located at http://technet.microsoft.com/en-us/
If you are going to use Microsoft PST Capture, you can import the .pst files to your
onpremises mailbox first and then do a migration, or you can import the .pst files directly to
cloud mailboxes. PST imports are bandwidth-intensive operations, so you need to take that
into consideration when scheduling and designing your PST import strategy.
Migration service throttling
In the migration exercises that you looked at earlier in this chapter, recall that you have
the ability to specify the number of mailboxes that are migrated simultaneously, which
by default is three. Specifying the number of mailboxes that should be simultaneously
migrated is referred to as migration-service throttling.
Refer again to the “Migration Performance” white paper or test a single mailbox migration
to determine the migration throughput. This will help you determine the optimum number
of simultaneous migrations your network can support.
User throttling mostly affects third-party migration tools. User throttling limits the number
of mailboxes a user can access simultaneously and is designed to minimize risks and
preserve resources. Therefore, if a migration tool uses a single service account with access to
all mailboxes, Office 365 might throttle the service account if it starts to access too many
mailboxes simultaneously during the migration process, thereby impacting migration
performance. When you evaluate migration tools, make sure that performance will not be
impacted by user throttling. Good migration tools generally use Exchange Web Services to
impersonate user accounts so Exchange Online is not seeing a single user simultaneously
accessing multiple mailboxes, but rather the users accessing their respective mailboxes.
Thus, user throttling will not be triggered.