SnapMirror with Vault Cascading

[Naimaws]

Question about a case of creating a SnapMirror(with vaults) Cascade. I believe this is by design, though I couldn't find it in the best practices guide . 

A...........B

Prod --> DR (Type: Mirror-Vault)    

The DR Site has SnapMirror snapshot, and many of the Snapvault snapshots.

Then, I did a SnapMirror (Type: Mirror-Vault)   to a 3rd Site, so:

A...........B..................................................C

Prod --> DR (Type: Mirror-Vault)    ---> 3rd Site (Type: Mirror-Vault)

At the 3rd site, we only see the SnapMirror snapshots (2 snapshots only and it doesn't bring the snapvault snapshots from DR).

So a few questions:

1. is there a way that would bring across all in the one snapmirror relationship?

2. if i were to break A-B, then do a snapmirror update on the 3rd site, would that update and then bring the snapvault snapshots?

3. could i create a new snapmirror relationship and specify just the snapvaults to copy across from B?

I've noticed the online KB mentions to move a snapvault target, you should break A-B, then mirror B-C, then break B-C and then resync A-C.  Is this  still current with the current version of 9.9.x? 

https://kb.netapp.com/Advice_and_Troubleshooting/Data_Protection_and_Security/SnapMirror/How_to_manually_move_a_SnapVault%2F%2FSnapMirror_Volume_to_a_...

[amccullo · Accepted solution]

The answers to the posed questions are listed below:


1. Yes, you have configured correctly for the most part, but are missing an important piece. The mirror-vault policy needs rules added to specify how many snapshots to move to the tertiary volume, based on snapmirror labels. Here is an example:

snapmirror policy add-rule -verserver Example1 -policy <policy name> -snapmirror-label daily - keep 25

The following link (first link) contains good information regarding this (under the headers Create Snapshot Policy on Primary Cluster and Create SnapMirror Policy on Secondary Cluster):

https://www.flackbox.com/netapp-unified-replication

https://docs.netapp.com/us-en/ontap/data-protection/supported-deployment-config-concept.html#how-fan-out-deployments-work

2. Yes, you could break the current relationship and mirror directly from A > C with a-sync mirror policy with MirrorAllSnapshots rule, but is unnecessary if you add the rules mentioned in the answer to Question 1. This KB discusses the policy types in more detail:

https://kb.netapp.com/Advice_and_Troubleshooting/Data_Protection_and_Security/SnapMirror/What_are_the_SnapMirror_policy_types_and_what_do_they_mean%3F

3. Yes, but again, that is unnecessary, as the policy modification should be enough to move the snapshots you wish.