topic Re: BIDIRECTIONAL SNAPMIRROR SYNC ? howto ? in ONTAP Discussions

BIDIRECTIONAL SNAPMIRROR SYNC ? howto ?

infogerance_cms — Thu, 05 Jun 2025 05:38:08 GMT

Hi,

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.

So how can I make that working ?

Regard's

Claude

Re: BIDIRECTIONAL SNAPMIRROR SYNC ? howto ?

radek_kubka — Wed, 16 Apr 2014 14:03:13 GMT

Hi Claude,

You can do it on a per volume basis, but for each relationship there is a distinction between source & destination.

So in other words you can do something like this:

SiteA\vol1 replicating to SiteB\vol1_mirror

SiteB\vol2 replicating to SiteA\vol2_mirror

Whether it is sync or async is irrelevant.

Regards,
Radek

Re: BIDIRECTIONAL SNAPMIRROR SYNC ? howto ?

infogerance_cms — Wed, 16 Apr 2014 14:24:29 GMT

Hi,

Let me just re-explain what I need ..

Site A/vol1 <== sync ==> SiteB/vol1 (SiteA/vol1 and SiteB/vol1 are rw)

So I need the same volume online and rw on both sites with a bidirectional replication.

I have read this in then net app pdf :

SnapMirror Sync and SnapMirror Semi-Sync

Overview and Design Considerations

TR-3326

But I can found no info in the manual to make it happen ..

Re: BIDIRECTIONAL SNAPMIRROR SYNC ? howto ?

radek_kubka — Wed, 16 Apr 2014 14:31:11 GMT

Not doable with SnapMirror.

You have something close to that in a MetroCluster setup, which uses SyncMirror (this is different from SnapMirror in sync mode) where reads can be done from both copies (plexes).

Re: BIDIRECTIONAL SNAPMIRROR SYNC ? howto ?

scottgelb — Wed, 16 Apr 2014 23:56:20 GMT

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.

Re: BIDIRECTIONAL SNAPMIRROR SYNC ? howto ?

ekashpureff — Thu, 17 Apr 2014 00:19:04 GMT

Claude -

I don't see a reference to whether this it's CIFS or NFS you're implementing, but I do see it's DOT 7.3.3.

(You may want to do an upgrade to a more recent version of DOT.)

There's also Flexcache you may want to look at.

With 7-mode it only works for NFS, but in Cluster it works with CIFS, too...

I hope this response has been helpful to you.

At your service,

Eugene E. Kashpureff

Senior Consultant, K&H Research http://www.khresear.ch/

Senior Instructor, Unitek Education http://www.unitek.com/training/netapp/

(P.S. I appreciate points for helpful or correct answers.)

Re: BIDIRECTIONAL SNAPMIRROR SYNC ? howto ?

infogerance_cms — Thu, 17 Apr 2014 07:58:11 GMT

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
Between HA pairs

I'm in 7.3.3 and it sound's like what I need.

So any idea how to put it in place ?

Re: BIDIRECTIONAL SNAPMIRROR SYNC ? howto ?

ekashpureff — Thu, 17 Apr 2014 08:13:22 GMT

Claude -

It's not going to work the way you're thinking about it.

The closest native solution with NetApp would be a Metrocluster install, as Radek mentioned above.

The most common Oracle solution for DR is using Oracle Dataguard to do the replication between sites, though there are SnapMirror fail over scenarios, too.

We discuss these topics on a deep dive in our Oracle on NetApp class.

I'm scheduled to teach it next the week of 5/12 on-line.

I hope this response has been helpful to you.

At your service,

Eugene E. Kashpureff

Independent NetApp Consultant, K&H Research http://www.linkedin.com/in/eugenekashpureff

Senior NetApp Instructor, Unitek Education http://www.unitek.com/training/netapp/

(P.S. I appreciate points for helpful or correct answers.)