VMware vVol replication has three components:
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Replication Policies (Storage Policy)
- Specify sets of VM requirements and configurations for replication that can be applied to VMs or virtual disks. If configuration changes violate a policy, VMs to which it is assigned become non-compliant
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Replication Groups (FlashArray Protection Groups)
- Correspond to FlashArray protection groups, and are therefore consistency groups in the sense that replicas of them are point-in-time consistent. Replication policies require replication groups
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Failure domains
- Sets of replication targets. VMware requires that a VM’s config vVol and data vVols be replicated within a single failure domain.
In the FlashArray context, a failure domain is a set of arrays. For two vVols to be in the same failure domain, one must be replicated to the same arrays as the other. In other words, a VM’s vVols must all be located in protection groups that have the same replication targets.
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Replication policies can only be assigned to config vVols and data vVols. Other VM objects inherit replication policies in the following way:
- A memory vVol inherits the policy of its configuration vVol.
- Managed Snapshots (and their chains) inherit the policy of the configuration vVol.
- vVols of Other type (such as digest or sidecar) inherit the policy of the configuration vVol.
- The swap vVol, which only exists when a VM is powered on, is never replicated.
VMware can perform three types of failovers on vVol-based VMs:
Planned Failover
Movement of a VM from one datacenter to another, for example for disaster avoidance or planned migration. Both source and target sites are up and running throughout the failover. Once a planned failover is complete, replication can be reversed so that the failed over VM can be failed back.
Unplanned Failover
Movement of a VM when a production datacenter fails in some way. Failures may be temporary or irreversible. If the original datacenter recovers after failover, automated re-protection may be possible. Otherwise, a-new replication scheme must be configured.
Test Failover
Similar to planned failover, but does not bring down the production VM. Test failover recovers temporary copies of protected VMs to verify the failover plan before an actual disaster or migration.
These vVol failover modes for can be implemented using the VMware SDK, tools such as Site Recovery Manager (SRM), PowerCLI or vRealize Orchestrator, or any tool that can access the VMware SPBM SDK.