There are many factors that can affect performance when migrating to Google Apps, including upstream bandwidth, internal network factors, workstation speed, available memory and database speed. The size of user’s mailboxes and the number of messages in them also affects performance. In order to get the best possible performance the first thing to ensure is that the migration station and all connections to and from it are as fast as possible. Following on from this, the way the tool is configured can also have a large impact in the speed at which a migration can proceed.
Usually the best way to obtain optimal performance, after making sure all local factors are as favorable as possible, is to migrate many users simultaneously. Google often restrict the speed at which users can be migrated, but this is on a per-user basis and not usually on a domain basis. This means that migrating one user (if the rate is limited for that user) can often take as long as migrating ten users. It is therefore advisable to migrate as many users as possible simultaneously.
Getting the best performance from the tool while migrating to Google Apps is to migrate many users simultaneously. Often, migrating one user can take as long as migrating ten users.
The number of users that can be migrated simultaneously can be affected somewhat by local bandwidth restrictions. For example, if there is limited upstream bandwidth, then in this case it can make sense to limit the number of simultaneous users that are migrated. If bandwidth is high, then migrating many simultaneous users is highly recommended to achieve the best throughput. An upper limit of 20 simultaneous users is recommended. With higher numbers performance can be adversely affected by CPU and memory usage.
To migrate more than 20 simultaneous users, we recommend setting up multiple migration workstations, each processing many users. This way CPU and memory is only an issue per-workstation and very large numbers can be migrated at one time, providing bandwidth is high.
A recent customer, migrating over 5000 accounts, was running 8 cloned workstations each processing 20 simultaneous users, and achieved migration of thousands of users in just a few weeks.
The best way to determine performance for your site is to perform a pilot migration with a representative number of users and examine performance. Often a migration of just one user may be carried out to ensure that mails, appointments and contacts are migrated correctly, but this alone does not give a true indication of the performance that can be obtained from migrating many users simultaneously. When the performance from your site has been established, a full migration plan can be established.
To set the number of simultaneous users the tool will process, adjust the setting ‘Maximum User Threads’ in the ‘System’ section of ‘Application Settings’. For more information, please also see the tool documentation installed with the program.
To discuss appropriate migration strategies for your site, please contact us and we would be happy to help.
To download the migration tool, visit our migration tool pages.