What are the SnapMirror policy types and what do they mean?
Applies to
- Clustered Data ONTAP 8.3
- ONTAP 9
Answer
SnapMirror policy types were introduced starting in clustered Data ONTAP 8.3 for Version-Flexible (also known as Unified Replication in ONTAP 9 and later) SnapMirror relationships. These policy types have a significant effect on the behavior of SnapMirror relationships and allow for greater flexibility when choosing what data is to be replicated and retained. Additional default policies have also been created to use the new policy types.
| Policy Type | Definition |
| async-mirror | Behaves similarly to DP mirrors. This policy type does not support rules with user-defined Snapshot labels. It only allows two predefined labels |
| sm_created & all_source_snapshots | The policy rules support only two combinations of these labels, either just sm_created or both sm_created and all_source_snapshots. |
|
mirror-vault |
Allows for both DR and Vaulting into the same volume. Replicates the active file system of the Source to the Destination and allows the Destination to retain data for a longer retention period. Data is replicated with either the sm_created or system-defined / custom rules and is retained for a longer duration with user-defined rules based of user-defined Snapshot labels. |
| vault | Vaults and backups only. This policy type is what defines a relationship as a SnapVault rather than a Version-Flexible SnapMirror. |
| sync-mirror & strict-sync-mirror | These policy types are used for synchronous Disaster Recovery and are supported only by Extended Data Protection (XDP) relationships between FlexVol volumes. All writes to the primary are replicated to the secondary before the write is acknowledged to the client. The strict-sync-mirror variant restricts further client IO on the primary upon a replication failure, whereas the sync-mirror variant does not. These policy types do not support replication of user Snapshot copies |
Default policies:
clusterA::> snapmirror policy show
Vserver Policy Policy Number Transfer
Name Name Type Of Rules Tries Priority Comment
------- ------------------ ------ -------- ----- -------- ----------
clusterA
DPDefault async-mirror 1 8 normal Default policy for DP relationship.
SnapMirror Label: sm_created Keep: 1
Total Keep: 1
clusterA
MirrorAllSnapshots async-mirror 2 8 normal Asynchronous SnapMirror policy for mirroring all snapshots and the latest active file system.
SnapMirror Label: sm_created Keep: 1
all_source_snapshots 1
Total Keep: 2
clusterA
MirrorAndVault mirror-vault 3 8 normal A unified Asynchronous SnapMirror and SnapVault policy for mirroring the latest active file system and daily and weekly snapshots.
SnapMirror Label: sm_created Keep: 1
daily 7
weekly 52
Total Keep: 60
clusterA
MirrorLatest async-mirror 1 8 normal Asynchronous SnapMirror policy for mirroring the latest active file system.
SnapMirror Label: sm_created Keep: 1
Total Keep: 1
clusterA
XDPDefault vault 2 8 normal Default policy for XDP relationship with daily and weekly rules.
SnapMirror Label: daily Keep: 7
weekly 52
Total Keep: 59
Additional Information
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