Configure SQL Mirroring for Lync CMS database
Towards the end of your Lync 2010 to Lync 2013 migration you would be migrating your CMS databases to Lync 2013 environment.
The actual migration of CMS from Lync 2010 to Lync 2013 is pretty straightforward and is documented at http://technet.microsoft.com/en-us/library/jj688013.aspx
One key point to bear in mind here is if you have SQL Mirroring configured for your backend SQL databases in Lync 2013 when you migrate your CMS (xds & lis databases) it will not be automatically replicated/mirrored. This needs to be manually configured.
To configure mirroring for the CMS databases use the following cmdlet: Install-CsMirrorDatabase -SqlServerFqdn “SQLSERVERFQDN” -DatabaseType “CentralMgmt” -fileshare \\SERVERNAME\FOLDERSHARE