I have 2 2020A clusters (dataontap 7.3.3), at the moment i use the sync snapmirror feature from site A to site B, that's working nice, but I have just find out that I can normally do a bidirectional snap mirror sync.
If cifs and you want the same data accessible at both sites, Peerlink from Peer Software is a good fit. It uses fpolicy and enforces locking on both sides with rw on both sides (or more) in a per cifs share basis. It isn't synchronous but when a file is written or updated, fpolicy notifies and the agent replicates the file to the other peers.
I it seem's I should be more precise in me need's :
I have 2 sites : SiteA - SiteB, on each I have a 2020A Cluster
I have 1 Volume for iscsi luns on SiteA that I sync to SiteB with snapmirror.
On the luns I have an OCFS2 filesystem so I can distribute in rw the same lun across 3 linux hosts (on SiteA and SiteB).
So wat will be nice is to have the same lun synced with snapmirror and in rw on both SiteA and SiteB, so that I can use multipathing on the linux box to have a complete fail over in case of crash on one of the sites.
In the Snapmirror overview an consideration pdf on page 7 I read this :
BIDIRECTIONAL SNAPMIRROR SYNC
Sometimes customers use both storage systems for primary workload and replicate data to each other to protect the primary data. Starting with Data ONTAP 7.2.2, bidirectional synchronous replication is supported in the following configurations for flexible volumes:
Between single controllers that are not part of an HA pair