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I want to test mirroring in Microsoft SQL Server Enterprise in order to decide if I would implement one in production. Buying another copy of SQL Server for another machine is not an alternative, given the high cost of the product.

When configuring the mirroring and specifying the same server as the mirror server instance, the following error is shown:

The principal and mirror server instances cannot be the same instance of SQL Server. Select another instance as the mirror server instance.

How can I test and discover mirroring feature of Microsoft SQL Server without having to purchase additional licenses?

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up vote 2 down vote accepted

You can install from the same media on another server without violating licensing; as long as the mirror secondary has equal or less processors than the primary. As long as you don't use it for active read-only connections, it doesn't need a paid license. See page 11[pdf], this is for SQL 2012, but there have been similar provisions as far back as I can remember.

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