Chapter 9. Disaster Recovery
Disaster Recovery (DR) helps an organization to recover and resume business critical functions or normal operations when there are disruptions or disasters. OpenShift Data Foundation provides High Availability (HA) & DR solutions for stateful apps which are broadly categorized into two broad categories:
- Metro-DR: Single Region and cross data center protection with no data loss.
- Disaster Recovery with stretch cluster: Single OpenShift Data Foundation cluster is stretched between two different locations to provide the storage infrastructure with disaster recovery capabilities.
- Regional-DR: Cross Region protection with minimal potential data loss.
9.1. Metro-DR
Metropolitan disaster recovery (Metro-DR) is composed of Red Hat Advanced Cluster Management for Kubernetes (RHACM), Red Hat Ceph Storage and OpenShift Data Foundation components to provide application and data mobility across OpenShift Container Platform clusters.
This release of Metro-DR solution provides volume persistent data and metadata replication across sites that are geographically dispersed. In the public cloud these would be similar to protecting from an Availability Zone failure. Metro-DR ensures business continuity during the unavailability of a data center with no data loss. This solution is entitled with Red Hat Advanced Cluster Management (RHACM) and OpenShift Data Foundation Advanced SKUs and related bundles.
You can now easily set up Metropolitan disaster recovery solutions for workloads based on OpenShift virtualization technology using OpenShift Data Foundation. For more information, see the knowledgebase article.
Prerequisites
Disaster Recovery features supported by Red Hat OpenShift Data Foundation require all of the following prerequisites in order to successfully implement a Disaster Recovery solution:
- A valid Red Hat OpenShift Data Foundation Advanced entitlement
- A valid Red Hat Advanced Cluster Management for Kubernetes subscription
To know how subscriptions for OpenShift Data Foundation work, see knowledgebase article on OpenShift Data Foundation subscriptions.
Ensure that the primary managed cluster (Site-1) is co-situated with the active RHACM hub cluster while the passive hub cluster is situated along with the secondary managed cluster (Site-2). Alternatively, the active RHACM hub cluster can be placed in a neutral site (Site-3) that is not impacted by the failures of either of the primary managed cluster at Site-1 or the secondary cluster at Site-2. In this situation, if a passive hub cluster is used it can be placed with the secondary cluster at Site-2.
NoteHub recovery is a Technology Preview feature and is subject to Technology Preview support limitations.
For detailed solution requirements, see Metro-DR requirements, deployment requirements for Red Hat Ceph Storage stretch cluster with arbiter and RHACM requirements.
9.2. Disaster Recovery with stretch cluster
In this case, a single cluster is stretched across two zones with a third zone as the location for the arbiter. This feature is currently intended for deployment in the OpenShift Container Platform on-premises and in the same location. This solution is not recommended for deployments stretching over multiple data centers. Instead, consider Metro-DR as a first option for no data loss DR solution deployed over multiple data centers with low latency networks.
The stretch cluster solution is designed for deployments where latencies do not exceed 10 ms maximum round-trip time (RTT) between the zones containing data volumes. For Arbiter nodes follow the latency requirements specified for etcd, see Guidance for Red Hat OpenShift Container Platform Clusters - Deployments Spanning Multiple Sites(Data Centers/Regions). Contact Red Hat Customer Support if you are planning to deploy with higher latencies.
To use the stretch cluster,
You must have a minimum of five nodes across three zones, where:
- Two nodes per zone are used for each data-center zone, and one additional zone with one node is used for arbiter zone (the arbiter can be on a master node).
All the nodes must be manually labeled with the zone labels prior to cluster creation.
For example, the zones can be labeled as:
-
topology.kubernetes.io/zone=arbiter(master or worker node) -
topology.kubernetes.io/zone=datacenter1(minimum two worker nodes) -
topology.kubernetes.io/zone=datacenter2(minimum two worker nodes)
-
For more information, see Configuring OpenShift Data Foundation for stretch cluster.
To know how subscriptions for OpenShift Data Foundation work, see knowledgebase article on OpenShift Data Foundation subscriptions.
9.3. Regional-DR
Regional disaster recovery (Regional-DR) is composed of Red Hat Advanced Cluster Management for Kubernetes (RHACM) and OpenShift Data Foundation components to provide application and data mobility across OpenShift Container Platform clusters. It is built on Asynchronous data replication and hence could have a potential data loss but provides the protection against a broad set of failures.
Red Hat OpenShift Data Foundation is backed by Ceph as the storage provider, whose lifecycle is managed by Rook and it’s enhanced with the ability to:
- Enable pools for mirroring.
- Automatically mirror images across RBD pools.
- Provides csi-addons to manage per Persistent Volume Claim mirroring.
This release of Regional-DR supports Multi-Cluster configuration that is deployed across different regions and data centers. For example, a 2-way replication across two managed clusters located in two different regions or data centers. This solution is entitled with Red Hat Advanced Cluster Management (RHACM) and OpenShift Data Foundation Advanced SKUs and related bundles.
Prerequisites
Disaster Recovery features supported by Red Hat OpenShift Data Foundation require all of the following prerequisites in order to successfully implement a Disaster Recovery solution:
- A valid Red Hat OpenShift Data Foundation Advanced entitlement
- A valid Red Hat Advanced Cluster Management for Kubernetes subscription
To know how subscriptions for OpenShift Data Foundation work, see knowledgebase article on OpenShift Data Foundation subscriptions.
Ensure that the primary managed cluster (Site-1) is co-situated with the active RHACM hub cluster while the passive hub cluster is situated along with the secondary managed cluster (Site-2). Alternatively, the active RHACM hub cluster can be placed in a neutral site (Site-3) that is not impacted by the failures of either of the primary managed cluster at Site-1 or the secondary cluster at Site-2. In this situation, if a passive hub cluster is used it can be placed with the secondary cluster at Site-2.
NoteHub recovery is a Technology Preview feature and is subject to Technology Preview support limitations.
For detailed solution requirements, see Regional-DR requirements and RHACM requirements.
