Google Apps Migration for Microsoft Exchange Administration Guide - Manual (Page 19)

Architecture and Deployment Scenarios 19
Parallel Processing
Each client machine simultaneously processes the number of users based on the user
restriction you specify. The utility defaults to 25. The amount of data processed at any one time
depends on the number of users you have configured for each client machine, and the number
of client machines you are using.
Google Apps Migration for Microsoft ® Exchange is capable of processing, and Google Apps
can receive, message data at the rate of 1 message per user per second. For example:
• 10 client machines each processing 25 users = 250 messages processed per second
• If each of those 250 users has 4,000 messages, you could process and migrate those
messages in 10,000 seconds, or 2.78 hours (250 users X 4,000 messages = 1M
messages; 1M messages/100 messages per second = 10,000 seconds or 2.78 hours)
In a magical world with no hardware constraints or network latency issues, you could process
and migrate message data at the rate of one message per user per second.
However, the speed at which you can reliably process and migrate data depends on:
• Physical resources on the client machine like CPU, memory, disk speed, and network
connection speed
• Physical resources on the Microsoft ® Exchange Server (or IMAP server) like CPU,
memory, disk speed, and network connection speed, along with how well you’ve tuned
your Microsoft
®
Exchange Server performance
• The overall speed of your network and your connection to external networks
• The density of traffic outside your network
Regardless of the actual speed at which you can process a single user, you can multiply the
amount of data you process by the number of users you process simultaneously on each client
machine, and by the number of client machines you use.
Our testing so far indicates that with Microsoft ® Windows Server 2003 and later, you can
optimally process 20-50 users at one time on a client machine, depending on that machine’s
configuration.