You can use the Block Volume service's replication feature for volume groups.
Volume group replicas themselves don't contain the full source data from the volumes in the
group. Instead, the volume group replica contains references to individual replicas for each
of the volumes in the group. This approach provides a seamless replication experience for
volumes whether they remain in the volume group, are removed from the volume group, or if
replication is turned off for the volume group itself.
When you activate a volume group replica, a new volume group is created. The activation
process is the same as creating a clone of the volume group.
This topic covers information about the replication feature specific to volume groups. For
general information about the replication feature and how it works, see Replicating a Volume.
Note
Replication doesn't cause any downtime or impact on source volumes.
Limitations and Considerations
The details specified in Limitations and Considerations apply to volume group replication, in addition to the following:
While it is possible to activate individual volume replicas separately from the
volume group replica, to ensure consistency, you should activate the volume
group replica instead. Activating the volume group replica ensures that all
replicas are activated from the same coordinated synchronization point.
When you remove a volume from a volume group, the volume is not available to add to
another group until removal process is complete.
When you add one or more volumes not configured for replication to a volume group that is
configured for replication, the Recovery Point Object (RPO) for the volume group
replication might degrade while the initial synchronization process runs for the
volumes added to the group.
To prevent this impact to the volume group's RPO, you can enable replication for the volume and wait until the initial synchronization process is complete before you add the volume to the group. To determine when the initial synchronization process is complete, monitor the status of the replica for the volume. After it has changed from Provisioning to Available the process is complete, and you can add the volume to the volume group without degrading the volume group replication's RPO.
When you configure replication for a volume group, if the group contains volumes that are already
configured for replication, the volume's destination region and availability
domain must match the volume group's destination region and availability domain
for replication. If they don't match, a Conflicting volumes message
occurs while creating the volume group. Remove these volumes from the group to
successfully create the volume group.
When you turn on replication for a volume group, all volumes in the group are included in the
volume group replica in the destination region and availability domain. Volumes
are no longer replicated individually, regardless of whether they were
configured for replication before they were included in a volume group with
replication turned on. You can no longer update the replication settings for an
individual volume, the settings must be configured at the volume group
level.
When you turn off replication for a volume group, by default all volumes continue to replicate,
but as separate volume replicas, they are no longer part of a volume group
replica. You can turn off individual volume replication for all volumes at this
point. Choose this option if you want to stop replication of all volumes. If you
want to continue replication of some volumes, but not others, do not select this
option. Instead, after replication for the volume group has been turned off, you
can turn off replication for individual volumes.
See the following topics for how to turn off replication for individual volumes:
Use the steps described in this procedure to enable replication on an existing volume group. You can also enable replication when you create a volume, see Creating a Volume Group.
Open the navigation menu and click Storage. Under Block Storage, click Volume Groups.
Click the volume group that you want to enable replication for.
Click Edit.
In the Cross Region Replication section, select ON.
For cross region replication, select the region you want to replicate the volume
group to, the availability domain to place the volume group replica in, and then
specify the name for the volume group replica.
For cross availability domain replication, select the same region the volume group is located in, the availability domain to place the volume group replica in, and then
specify the name for the volume group replica.
Optionally, encrypt the volume group replica in the destination region by using your own Vault encryption key. Select Encrypt using
customer-managed keys for Cross region replication
encryption, and then specify the OCID for a valid encryption key
in the region you selected to replicate the volume group to. For more
information, see Requirements for Customer-Managed Encryption Keys for Cross-Region Operations.
To change the destination region or availability domain for cross region replication you
need to first turn replication off for the volume group. Then specify the new region and
availability domain selections when you turn replication on again.
Open the navigation menu and click Storage. Under Block Storage, click Volume Groups.
Click the volume group that you want to change the replication settings for.
Click Edit.
In the Cross Region Replication section, select OFF.
Check CONFIRM to acknowledge the that volume group replica will be
deleted.
Click Save Changes.
Click Edit.
In the Cross Region Replication section, select ON.
For cross region replication, select the region you want to replicate the volume
group to, the availability domain to place the volume group replica in, and then
specify the name for the volume group replica.
For cross availability domain replication, select the same region the volume
group is located in, the availability domain to place the volume group replica
in, and then specify the name for the volume group replica.
Optionally, encrypt the volume group replica in the destination region by using your own Vault encryption key. Select Encrypt using
customer-managed keys for Cross region replication
encryption, and then specify the OCID for a valid encryption key
in the region you selected to replicate the volume group to. For more
information, see Requirements for Customer-Managed Encryption Keys for Cross-Region Operations.
For volumes in a volume group configured for replication, activate the
volume group replica instead of individual volume replicas if you want to ensure that
all volume replicas are activated from the same coordinated synchronization point. See
Limitations and Considerations.
To create a new volume group from a volume group replica, you need to activate the
replica. The activation process creates a new volume group by cloning the replica.
Open the navigation menu and click Storage. Under Block Storage, click Block Volume Replicas. Ensure that you're in
correct destination region and availability domain that contains the volume group
replica you want to activate.
Click the replica that you want to activate.
Click Activate to open the Activate Volume Group Replica form.
On the Activate Volume Group Replica, specify the compartment and the name
for the new volume group, and optionally select the cluster placement group.
Note
The Cluster Placement Group control only
appears in the Console if Cluster Placement
Groups are enabled for the tenancy, and you've created and activated a cluster
placement group with the capability added for volume resources, see Cluster Placement Groups for Block Volume.
Click Create. The new volume group appears in the volume groups list, in the
provisioning state.
The volume group replica's details page provides information about the replica's
status.
Open the navigation menu and click Storage. Under Block Storage, click Volume Groups. Ensure that you are in the destination region containing the volume group replica that you want to view.
Click the replica that you're interested in.
The replica details page displays the following relevant fields:
Last Sync: The time of the last data synchronization from the source volume group to the
replica.
Total Data Transfered: The amount of data, in GBs, that has been transferred during the
replication process for the volume group. This includes all data from the
point that replication was enabled to now.
To failback a volume group replica to the source region, you need activate the volume
group replica in the destination region, with replication enabled, and select the
original source region as the target region for replication.
Open the navigation menu and click Storage. Under Block Storage, click Block Volume Replicas. Ensure that you are in correct destination region that contains the volume replica you want to activate.
Click the replica that you want to activate.
Click Activate to open the Activate volume group replica form.
On the Activate Volume Group Replica, specify the compartment and the name
for the new volume group, and then click Create. The new volume group will
appear in the volume groups list, in the provisioning state.
Ensure that
Volume Replication is enabled, and select the original source
region.
Once the volume group has been created, turn on replication for the volume group and
specify the original source region as the destination region. See To enable replication for a volume group.
Once the initial synchronization finishes, the failback process is complete, and you
can activate the volume group in the original source region.
For volumes in a volume group configured for replication, activate the
volume group replica instead of individual volume replicas if you want to ensure that
all volume replicas are activated from the same coordinated synchronization point. See
Limitations and Considerations.
You can enable replication for volume group when you create or update the group. To
disable replication, use the Update operation. To activate a volume
group replica, use the Create operation and pass the source volume
group's replica ID.