The comm_dssetup.pl script asks you to specify which schema version Directory Server is to use by setting the comm_dssetup.pl -t option, as follows:
-t 1— Schema 1
-t 1.5— Schema 2, compatibility mode
-t 2— Schema 2, native mode.
Since you are upgrading your Messaging and Calendar servers before you migrate to Schema 2, you should specify Schema 1 at this stage. If you specify Schema 1 when you run comm_dssetup.pl, the upgraded servers will continue to use the existing schema without interruption.
If you also have installed Calendar Server 6 and have already run comm_dssetup.pl, you might not need to run the script again.
You only need to run comm_dssetup.pl once for each Directory Server used by the Messaging and Calendar servers. However, if you are not sure what to do, it will not hurt your system to run it again. In fact, the script checks to see if the current version has already been installed and will notify you.