How long does it take to migrate a mailbox?

This is really the million dollar question. Unfortunately, I can’t give you a definitive answer and no one else will be able to also. There are many factors that will affect the duration of a migration. The following is a list of things that affect majority of the speed and dictate how long it’s going to take:

Network Speed – How fast is source and destination server connected to the internet? If you are migrating to and from a hosted environment, this isn’t a concern most of the time. You don’t need to worry about our network speed, depending on the data center that the migration server is located in, we will be connected with a gigabit or 10-gigabit connection.

Network Latency – The network latency is dependent on the quality of the connection between our data center and the source and destination. We utilize the fastest internet backbones available globally. We sometimes encounter connections to servers that look like they were purchased from a flea-market.

Number of Mailbox Items – There is a per-item transaction overhead. For example, given two mailboxes with the same size but different number of items, the one with less items will migrate faster than the one with more items.

Size of Mailbox – This one is obvious. The more data you have, the longer the migration.

Number of Errors During Migration – Errors can occur for a number of reasons, and when they do, out error logic kicks in. But when it does, we perform an exponential back-off (I’ll cover this in a later port) which increases the duration of the migration for that mailbox. If you don’t change the default settings for error handling, a single error failure increases the length of your migration by 15 minutes. Note that recoverable errors (errors that do not reach the retry threshold) are not recorded as they were successful before the maximum retry amount. Most errors are caused by network connection or the server tried to throttle us because we were attempting too many transactions.

Server Load – What type of equipment is the source and destination mailbox deployed on? We are adding extra load onto the server since we are accessing your mailbox. Also depending on the time and day, the user load fluctuates.

Connector Type – Each connector type has different overheads per-item. Some have more overhead than others.

MigrationWiz Data Center – We load balance migrations across many servers around the world to ensure there is no single point of failure, and achieve optimal performance. Chances are that if you migrate more than one mailbox, they are all distributed across many servers and even in multiple geographical locations. Because they are different servers and potentially different locations, the network conditions may be different. To ensure that we are never the bottleneck, we leverage the fastest backbone to the internet in addition to deploying some the biggest servers we can get our hands on.

I wish I could give you a formula to plug this into but if I can’t. If you are migrating all of the mailboxes for your company at the same time, a good rule of thumb is that the time it takes to move everyone over is the time it takes to move the largest mailbox.