UNDO options in an #Oracle Calendar Server to #MSFTExchange migration

We were dealing with a client who needed to do an UNDO of a previous test migration and this meant we gave the site a concise summary of their options.

Of which there are three.

The fastest: dismount the stores, delete the database file(s) and logs, and then remount the stores.  This clears everything from all provisioned accounts!   This is the nuclear option on the data. It’s OK to do IN A TEST ENVIRONMENT.  It will cause a “resume-generating” action if done in production.  Remove the guest response database and start a new insertion.  Note that you will not need to re-provision the mailboxes. That’s what’s so good about this option:  Exchange remembers that accounts/users are already provisioned in Active Directory and Exchange recreates mailboxes once meeting invitations start flowing in.

Remember, if anyone else is working on the server, the nuclear options wipes their data.

Here's an example of how to script the removal of two databases "mbx01" and "mbx02"

d:
cd "D:\Ex13DB\"
Dismount-Database "mbx01" -confirm:$false
Dismount-Database "mbx02" -confirm:$false
remove-item -Path mbx01 -recurse -force
remove-item -Path mbx02 -recurse -force
Mount-Database "mbx01" -force
Mount-Database "mbx02" -force

Next fastest: Keep the guest response DB and do an UNDOALL.   This clears everything and the guest response table. Then delete the guest response DB and start a new insertion.

The slowest but safest: keep the guest response DB do a regular UNDO.  Then remove the guest response DB and start a new insertion.