In September I released our guidance on how to lay out database copies to ensure symmetrical distribution of the active copies in the event of a failure. This guidance was further expanded and released as a TechNet article in November. Feedback from the community was very clear – you guys wanted a tool to help you lay out your database copies correctly.

Well I am pleased to say that with this release of the calculator, we have delivered. Over the last several months, two gentlemen from MCS, David Mosier and Neil Johnson, worked tirelessly to bring this functionality to reality.

On the Input worksheet, within the Database Configuration table, you can now have a new option, “Calculate Number of Unique Databases / DAG for Symmetrical Distribution”. When this option is enabled, the calculator will use the permutation formula discussed in our guidance to deploy the correct number of databases based on the number of copies and server architecture such that you can potentially achieve a symmetrical distribution after a failure event.

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The calculator includes a new worksheet, Distribution. Within the Distribution worksheet, you will find the layout we recommend based on the database copy layout principles.

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The Distribution worksheet includes several new options to help you with designing and deploying your database copies:

  • You can determine what the active copy distribution will be like as server failures occur within your environment.

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  • You can export a set of CSV and PowerShell scripts that perform the following actions:
    • Diskpart.ps1 (uses Servers.csv) - Formats the physical disks, and mounts them as mount points under an anchor directory on each server.
    • CreateMBDatabases.ps1 (uses MailboxDatabases.csv) - Creates the mailbox database copies with activation preference value of 1.
    • CreateMBDatabaseCopies.ps1 (uses MailboxDatabaseCopies.csv) - Creates the mailbox database copies with the appropriate activation preference values across the server infrastructure.  

Important: The database copy layout the tool provides assumes that each server and its associated database copies are isolated from each other server/copies.  It is important to take into account failure domain aspects when planning your database copy layout architecture so that you can avoid having multiple copy failures for the same database.

Hopefully you will find these changes worthwhile in your deployment of Exchange 2010.  Now, go tryout the new version of the calculator and let us know what you think.  Alternatively, you can check out what else has changed by reviewing the Updates Tracking page. The main article has also been updated.

Ross Smith IV, David Mosier, Neil Johnson