The continuous replication feature uses block-level replication to synchronize block devices or virtual machine disks, continuously streaming updates from source to destination VMs. Each source VM and the resulting destination VM is a replication pair. vSphere APIs for I/O Filtering (VAIO) is a VMware framework that enables block-level replication of virtual machine data. You can configure continuous replication only for on-premises VMware instances. You cannot configure continuous replication for cloud instances, such as VMC, Dell-EMC, Oracle Cloud, and others.
Note: From 11.20, the Command Center uses the name "continuous replication" instead of "Live Sync I/O".
Block-level replication provides the following benefits:
Eliminates the need to take and clean up snapshots frequently on the source VM, reducing the I/O impact on the production system.
Enables more frequent and granular updates and synchronization between source and destination VMs, making it possible to meet reduced recovery time objectives (RTOs) and recovery point objectives (RPOs) for virtual machines.
Provides a dynamically pruned history of recovery points without running backups or relying on synthetic full backups to consolidate incremental updates for different points in time.
You can configure and run continuous replication from Command Center or the CommCell Console.
After you configure a replication group for continuous replication, backup and replication begins automatically. The backup of the source VM provides the initial image for the creation of the destination VM. Replication is automatically enabled to capture subsequent updates to the source VM.
Note: Continuous replication is supported only from streaming backups. It is not supported from IntelliSnap backups.
Recovery points are crash consistent copies of volumes on the destination VM that match the data that was written on the source VM volumes at a specific point in time.
Application-consistent backups that are performed with the assistance of application agents or by performing VSA backups create application-consistent recovery points (ACRPs).
ACRPs are based on application-consistent VM snapshots. If a replication pair is configured for ACRPs, the replication service periodically creates temporary application-consistent snapshots on the source VM. The Recovery Point Store (RP Store) on the destination site records ACRPs as point-in-time recovery points.