Accurately determining how much time it takes to migrate email data to Rackspace is difficult because of several factors, including system load, bandwidth, average item size, and source or destination bottlenecks. Migrations of mailboxes that are between 350 MB and 1.5 GB typically take up to an hour, and you can migrate groups of mailboxes overnight.
The following sections provide more detail about the factors that can affect how long a migration can take to complete.
Simultaneous mailbox migrations
Our email migration tool has reached speeds of over 1.5 GB per hour per mailbox when connecting to high availability infrastructures. Migrating more mailboxes at the same time allows parallel processing and reduces the duration of your migration.
Our email migration tool can migrate hundreds of thousands of mailboxes simultaneously. If you migrate all of your mailboxes at the same time, the migration duration is the time it takes to migrate the largest mailbox.
How fast are the source and destination servers connected to the Internet? The email migration server is only as fast as the slowest link. The migration server can work across even the slowest links, connecting to networks that range from T1 speed to networks that host multiple gigabit connections.
The network latency depends on the quality of the connection between the source and destination servers.
Number of mailbox items
Mailboxes with more email messages take longer to migrate. For example, if two mailboxes are the same size but have a different number of items, the mailbox with fewer items migrates faster than the mailbox with more items. The servers talk to each other to introduce each message, so multiple messages have more overhead from network chatter than a single large message.
The email migration server greatly reduces network chatter. It has moved over a thousand items in less than a minute in some cases.
Although the volume of data in a mailbox can affect migration duration, the number of items in a mailbox has a much greater impact on the duration of an email migration.
Errors can occur for many reasons, including corrupt items and network outages. Our email migration team has tools with self-healing technology that can automatically manage errors in most cases.
If the source or destination system throttles the amount of data the system can read or write, the migration might not be able to use all the available network bandwidth.