Concept
Replication Patterns
The policy layer for controller-backed replication and disaster-recovery target readiness.
Definition
A replication pattern is the Sendense policy that defines disaster-recovery replication behavior: which workloads are replicated, where their recovery-side replicas live, how recovery readiness is maintained, and how failover workflows are coordinated.
- Which workloads participate in the replication workflow.
- The recovery site and destination platform, with placement settings such as template, network, disk offering, service offering, and zone where applicable.
- The replication network for target-side replication traffic, the recovery network used when a workload boots during failover, and optional test network overrides.
- The sync interval, presented as the pattern RPO target, and whether manual full resync is available.
- The replication route policy and pattern-level sync concurrency and queuing behavior.
Patterns And Targets
A replication pattern is the policy. A replication target is the per-workload target created under that policy. Each target tracks the source workload, destination placement, controller VM, sync schedule, last sync state, and failover lifecycle state.
Operators can trigger a pattern-wide sync that fans out across the assigned targets. Sendense starts some syncs immediately, queues others when concurrency limits are reached, skips targets that are not syncable, and reports where a sync request cannot be accepted.
Controller-Backed Targets
When a replication pattern uses controller-backed targets, Sendense provisions one controller VM per protected VM after the required controller template is available in the destination system.
Replication Route Policy
Each pattern carries a replication route policy that controls how replication data travels between the protected site and the recovery site. Automatic lets Sendense choose the best route for each sync, Via SHA sends data through the encrypted appliance connections via SHA, and Direct P2P sends it directly between the two site SNAs after a live reachability check.
Sync Lifecycle
The pattern's sync interval is the target RPO for its workloads. RPO status is an operational measurement based on last successful sync and current target state, not a guarantee under every condition.
Sync lifecycle
Baseline
Initial Sync
The first full population of the controller-backed target's replica disks.
On schedule
Incremental Syncs
Recurring syncs at the pattern interval transfer changes since the last successful sync. Operators can also trigger manual syncs or a full resync.
RPO status
Readiness Tracking
Last sync, next sync, controller health, and RPO status feed pattern health and failover readiness.
Exception path
Interrupted Sync
A sync stops before completing, for example after a network interruption.
Operator-visible step
Checkpoint Recovery
Sendense recovers the sync checkpoint so normal syncs can resume safely.
Back on schedule
Normal Syncs Resume
Scheduled incremental syncs continue at the pattern interval.
Pattern-Level Failover
Replication patterns support failover for a single VM or across the pattern. A pattern failover processes the eligible targets, can run multiple VMs in parallel, and lets operators limit parallelism and choose whether to continue with remaining VMs if one VM fails.
Test failover keeps rollback available. Planned failover powers down the source where possible, runs a final sync, and starts the recovery-side workloads. Emergency failover starts recovery-side workloads from the latest available sync point when the source is unavailable. After a planned or emergency failover, the operator commits to finalize or rolls back while rollback remains available.
Replication Patterns And Protection Patterns
Protection patterns and replication patterns are both policies orchestrated by SHA, but they serve different goals. A replication pattern is not a backup retention policy and does not store backup data.
Related Docs