You should consider the following operational points for the RSG before using it:
You can't restore a public store to the RSG-it supports only mailbox stores.
When an RSG is present on a server, Exchange Server automatically directs all restore operations to the RSG. If you want to perform a typical restore and attempt to restore a database that isn't present in the RSG, Exchange signals error 9634 Failed to find a database in the Recovery Storage Group, which is logical. To prevent problems with typical restore operations, remove the RSG from a server when it's no longer required. However, if you want to keep the RSG in place, you can create the DWORD registry value Recovery SG Override in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem subkey and set the value to 1 to force utilities that use Exchange's backup API to ignore the RSG.
MAPI is the only protocol that you can use to access data in a mailbox store in the RSG. However, MAPI programs need to understand the structure and connections that exist between the RSG and the data in the mailbox store. Both Exchange System Manager (ESM) and the version of ExMerge that's distributed with Exchange 2003 have been adapted to deal with the RSG. In general, always use the latest version of these utilities-the version of ESM in Exchange Server 2003 Service Pack 1 (SP1) is better than that from Exchange 2003.
You can't use RSG to recover mailboxes for deleted users or those who've moved to another storage group.
Clusters support one RSG per Exchange virtual server. You can restore mailbox stores from standalone servers to an RSG on a cluster, providing that the servers are part of the same administrative group as the cluster.
You can restore a database to the RSG on another server in the same administrative group. However, the name of the database and the storage group must match on both the source and target server. If the names don't match, follow the suggestions outlined in the Microsoft article "You cannot restore a mailbox store from one Exchange 2003 server to a Recovery Storage Group on another Exchange 2003 server," http://support.microsoft.com/?kbid=836554, and retry.
Although the RSG can run only on an Exchange 2003 server, you can connect databases from any server in the administrative group, including servers running Exchange 2000 Server SP3 and later. However, when you use the RSG to recover data from these databases, the Store automatically upgrades the database version to the version used by the server that hosts the RSG. Thus, you can't then switch the recovered database back to its original server unless you update that server to run the same version of Exchange. For much the same reason, you can't use RSG to recover data from a server that's running a newer version of Exchange.
Microsoft has published an excellent document containing many tips and techniques about how to use the RSG in your deployment. For more information, check out Microsoft article "The 'Using Exchange Server 2003 Recovery Storage Groups' book for Microsoft Exchange Server 2003 is available," http://support.microsoft.com/?kbid=836452.