Exchange 2007 uses the RSG (Recovery Storage Group) mechanism. RSG allows the user to mount a second copy of an Exchange information store on any Exchange Server that is a member of the same Exchange Administrative Group as the original while concurrently the original information store is still active. This allows the user to recover data from the backup copy of the information store without interfering with the on-going operation of the Exchange Server.
Once the RSG has been created the user first restores the backup to it and then uses the Microsoft Exchange Management Shell in Exchange 2007 to extract mailbox data from the information store into the local mail .pst file. The user may also optionally merge the extracted data back into the currently active information store as well.
RSG is fundamentally different than the recovery database mechanism used in Exchange 2013 and 2010.