Reading the documentation for VCS 5SP2 it seems that there is no way to guarantee multi-LUN consistency using VCS and MirrorView/Sync. As long as all mirrors are in-sync (normal state) you’d be fine, but if something caused some of the mirrors to become out of sync, while others were still syncing, you’d have data consistency problems if the primary site failed suddenly. Consistency groups would help but you have to use Mirrorview/Async in order for VCS to support it. The scenario when this will matter is if the primary site goes down, while at the same time there was some sort of issue with one of the mirrors causing it to not be in sync. VCS will see that not all of the mirrors were in-sync and will fail to promote the secondary site to come online, waiting for admin action. At that point you’d need to restore from backup or some other copy.  You could probably use scheduled clones or snaps on the target side to create a gold copy. That way if the primary site failed and the mirrors were not all in-sync, you could roll the mirrors back to a known good point in time from the clones or snaps and come online.  The issue with using clones/snaps to guarantee your consistency is the potential of how much data would be lost in that scenario. If you had clones every hour you could lose up to 1 hour of data if you had to roll back. Using MirrorView/Async would get the consistency group functionality but you’d ALWAYS have some data loss in an unplanned disaster. How much depends on how often MV/A updates the secondary copy, which could be as low as a few minutes.  In a coordinated failover, where both arrays are online and seeing each other, VCS will make sure that the failover keeps data consistent, whether using Synch or Async, it’s only the case of sudden primary site outage where VCS can’t guarantee consistency, since it’ can’t ask the primary array to update the secondary before coming online.  Richard J Anderson
Hi all, It is new project requirement. Recently setup one RHEL system per each site. And Configured 4 luns for DB and 1 lun for Archive logs, To set the mirror view/sync across sites,what would be the best practice.. Create 2 consistency groups ,one for DB luns and one for archive logs ? or shall we go ahead with each lun setup..? It is setup as Geo-cluster, means VCS mirror view agent will failover automatically if any failures observed in production host....
Mirror view /sync setup for Oracle DB