IN THIS ARTICLE
Outlines how to configure and use Snapshot Policy Replication in Qumulo Core
- Source cluster running Qumulo Core 2.14.0 or later
- Target cluster running Qumulo Core 2.13.5 or later
Snapshot Policy Replication enables you to automatically take snapshots of the data in your replication relationship's target directory, ensuring that even if bad data or changes are inadvertently replicated over to the target, a backup snapshot of the valid data remains. Using this feature, you can link up to ten existing snapshot policies to a replication relationship. Once you’ve established the link, replication will take care of the rest by replicating future snapshots taken by those policies to its target directory.
Once each replication job completes, a new snapshot of the target directory is taken to ensure that the data is consistent on both the source and target clusters and that a snapshot history of the file changes exists. You can specify how long you wish to keep the snapshots, either manually or by setting it to use the same expiration as is configured in the snapshot policy.
NOTE: In order to enable Snapshot Policy Replication, you must have at least one snapshot policy for the directory being replicated already configured on your source cluster. See Snapshots: Per-Directory Snapshots for additional information.
Configure Snapshot Policy Replication
- Login to the Web UI.
- Hover over the Cluster menu on the Source cluster and select Replication under the Configurations section in the dropdown.
- Click Create Relationship to create a new replication relationship.
- Provide the required details for the source and destination directory paths, as well as the destination IP for your replication cluster.
- In the Replication Mode section, select the type of replication you wish to enable:
- Continuous Replication: use replication without binding it to a specific snapshot policy. See Replication: Continuous Replication with 2.11.2 and above for further details.
- Snapshot Policy Replication: configure replication to replicate only snapshots taken based on the policy (or policies) linked. If no new snapshots from the policies are present, replication will take no action.
- Snapshot Policy with Continuous Replication: if no new snapshots are discovered, replication will take an on-demand snapshot and replicate it to the target whenever any changes to the source directory have been detected. This option is recommended for most configurations, as it ensures that data is continuously kept up to date on both source and destination clusters.
- Select the snapshot policy of your choice in the Policy drop-down.
- Click the desired snapshot expiration policy under Expire Snapshot on Target. Link additional snapshot policies by clicking + Link Snapshot Policy and repeat steps 5-7 for up to 10 policies.
- Same as policy: Snapshots on the target cluster will be deleted on the same schedule as configured in the linked snapshot policy.
- Never: Snapshots will never be deleted on the target cluster.
- Automatically after [DURATION]: Snapshots will be deleted after the specified amount of time has elapsed.
- Click Add Blackout Window if you wish to configure days or times to suspend the replication process. For additional details, check out the Replication: Blackout Windows article.
- Enable the Map Local User/Group IDs to Associated NFS IDs option if you wish to replicate files using locally-owned NFS IDs. See the Replication: NFS ID Mapping article for full details.
- Confirm the Enabled box is checked under Enable Replication to activate the replication relationship.
- Click Save Relationship.
- Login to the the Web UI of your target cluster and click the See details link in the announcement banner to view the Replication page.
- Click the Authorize link in the Status column for the relationship to grant it authorization on the Replication page.
Now that the relationship is established, any new snapshots taken by the linked snapshot policies are automatically queued to be replicated to your target cluster.
View Snapshot Policy Replication Details
Once a Snapshot Policy Replication relationship has been established, you can easily view the snapshots governed and replicated by it from the Replication Relationship table.
- Click the menu underneath the Actions column on the replication relationship listing.
- Click View Relationship Details to see the snapshot policies linked to the selected replication relationship.
A list of queued snapshots is provided in the table below the Linked Snapshot Policies. These snapshots are considered locked by the snapshot policy (and thus cannot be deleted). To prevent a specific snapshot from being replicated via the queue, click the Release... link provided for the snapshot. This removes it from the replication queue but does not delete the snapshot itself. Released snapshots can either be manually deleted or automatically when the snapshot expires.
NOTE: If the relationship has a lot of data to replicate (i.e., when it's first created and linked to an existing snapshot policy), it may take some time to complete. During this time, additional snapshots may accrue depending on the frequency of your snapshot policy configuration. These snapshots will queue up until they are replicated, at which point they will vanish from the table.
- Snapshot Policy Replication requires the target cluster to be running Qumulo Core 2.13.5 or later for full functionality. It can be enabled in a replication relationship with a target cluster running an earlier version, but its functionality may be limited:
- If the target cluster is running Qumulo Core 2.13.0 or 2.13.1, snapshots taken according to a linked snapshot policy will be replicated to the target but not retained past the next successful continuous or policy-initiated replication job.
- If the target cluster is running Qumuo Core 2.13.2 through 2.13.4, snapshots taken according to a linked snapshot policy will be replicated to the target and retained according to the target expiration time defined in the replication relationship. However, the name of snapshots on the target will not reflect the source snapshot policy’s name nor will the creation time of the target snapshots match the creation time of the replicated source snapshot (instead, the creation time of the snapshot will reflect the time its associated replication job finished on the target).
- If the target cluster is on release 2.13.5 or later, all Snapshot Policy Replication functionality is available.
- A snapshot policy can only be linked to one replication relationship at any given time. Attempting to link the same policy to multiple relationships will result in an error: “The snapshot policy is already linked to another replication relationship.”
- Disconnecting a replication relationship will not stop its linked snapshot policy from continuing to take snapshots.
- Reversing a replication relationship will unlink any snapshot policies from the now-target relationship. Any snapshots queued for replication will be unlocked as well. These snapshots will retain the expiration policy originally configured at the time they were replicated.
- Reversing a relationship from target to source that previously had linked snapshot policies will re-link those snapshot policies, thus also re-locking them. If the snapshot policy was deleted while the relationship was reversed, it won’t be re-linked. If all policies have been deleted, the replication relationship will be set back to Continuous Replication.
- When linking a snapshot policy, only new snapshots for that policy will be replicated. By the same token, changing the target expiration period of an existing Snapshot Policy Replication relationship applies only to snapshots taken after the configuration change.
You should now be able to successfully use Snapshot Policy Replication with Qumulo Core
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