Video Series: Exchange 2007 SP1 Standby Continuous Replication (SCR)

Len, to configure multiple SCR targets for the same storage group, you simply repeat the Enable-StorageGroupCopy task (with the -StandbyMachine parameter pointing to the new target) for each additional target you want to create.  To configure storage groups on multiple clustered mailbox servers for SCR using the same target, you simply use the same StandbyMachine for those storage groups. Note that the OS on the SCR source and targets must match, and you must not have any storage group or database path collisions between the SCR sources and all targets.

Once you have both CMS' replicating their storage groups to the same standby server, the way in which you activate that server depends on the nature of the failure.  If you lose just a single SG/DB, you will find database portability to be the best way.  If you lose an entire CMS, then you can use the recovery option.  However, in that case, be aware that the SCR target computer must be a passive node in a failover cluster that does not contain any CMS in the cluster. This is required in order to leverage Setup /recovercms.  Also be aware that you will need to suspend SCR for the other, healthy CMS, and then reconfigure SCR after you have recovered your standby cluster.