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Why is my Exchange 2013 mailbox migration moving slowly?

My mailbox migration from Exchange 2010 to Exchange 2013 is moving very slowly. What might be causing this and how can I speed up the process?

Moving mailboxes from one version of Exchange to another is a relatively easy concept; however, it may be easier said than done.

Testing individual mailbox moves can lead to a false sense of security that breaks during batch migration.

In this case, the moves are slow, which confirms that the Exchange infrastructure is functional. There are numerous factors that could impact the speed of the moves, but without some analysis of the system it can be difficult to pinpoint.

Four core resources should be analyzed on the source and target servers: processor, memory, disk and network. A bottleneck in any of these areas on the server can cause slow mailbox moves. However, if analysis of these core resources does not indicate performance bottlenecks, dig deeper into the actual move statistics.

Exchange Server 2013's Managed Availability also provides server health information. Use the Get-HealthReport cmdlet to display the server's health. The downside is it will only report on the 2013 server's health. Use the Get-MoveRequestStatistics cmdlet during and after mailbox migrations to obtain detailed information. Modify the MxExchangeMailboxReplication.exe config file on Exchange 2010 and 2013 servers. Specifically look at modifying the following default settings:

  • MaxActiveMovesPerSourceMDB="5"
  • MaxActiveMovesPerTargetMDB="2"
  • MaxActiveMovesPerSourceServer="50"
  • MaxActiveMovesPerTargetServer="5"

Use the AnalyzeMoveRequestStats.ps1. Although this script was written for Office 365 migrations, it works with on-premises migrations as well.

About the author:
Richard Luckett is a consultant and instructor specializing in messaging and unified communications. He's been a certified professional with Microsoft since 1996 and has 20 years of experience in the public and private sectors. Luckett is a Microsoft Certified Trainer with more than 15 years of training experience with the Microsoft product line and received the Exchange MVP award in 2006, 2007 and 2008. He's also an expert in deploying and integrating Exchange Server and Lync Server. He leads the Microsoft training and consulting practice at LITSG.

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