Query regarding Netapp files CRR replication

For Azure NetApp Files cross-region replication (CRR), there is no fixed, size-based failback time published for an 11‑TB dataset. The actual duration depends on:

• The amount of data that changed while running in DR
• The replication schedule configured (every 10 minutes, hourly, or daily)
• Network throughput and any replication lag

From Microsoft guidance:

1. Failover and failback are manual processes
   • For a region failure, failover requires breaking the peering and mounting the destination volume in the DR region. After the peering is broken, the storage-side failover itself typically completes within about one minute. Overall RTO is usually a few minutes to an hour, depending on how quickly the environment detects the issue and initiates failover.
   • After the primary region recovers, failback is also manual and requires:
     • Performing a resync operation
     • Reestablishing replication in the desired direction
     • Remounting the source volume for clients
2. Replication behavior and RPO
   • CRR is asynchronous; changes are replicated on the schedule configured:
     • Every 10 minutes (not supported for large volumes that use CRR)
     • Hourly
     • Daily
   • Typical RPO values are tied to that schedule (for example, 10‑minute schedule → typical RPO < 20 minutes). The longer the schedule, the more potential data loss in a disaster, but the less replication overhead.
3. Best-practice approach for failback
   Microsoft best practices for Azure NetApp Files DR with CRR are:
   • Plan and document the direction change: After failing over to DR and running there, when ready to fail back:
     1. Ensure the DR volume is in a healthy state and all application writes are quiesced before starting failback.
     2. Perform a resync from the DR volume back to the primary region volume to reestablish replication in the reverse direction.
     3. Once resync is complete and replication is healthy, perform the failback cutover by:
        • Breaking peering as needed
        • Mounting the now-active volume in the primary region to the application hosts
        • Redirecting application traffic back to the primary region
   • Traffic rerouting is the application owner’s responsibility: After failover or failback, application endpoints must be updated to point to the newly active volume.
   • Monitor replication health and lag: Use Azure Monitor metrics and the CRR health views to ensure replication is caught up before cutover.
4. “Waiting a few days” on DR
   There is no Microsoft requirement to stay on the secondary site for several days purely to “sync correctly.” The key requirement is that the replication relationship is healthy and fully caught up before performing failback. How long that takes depends on:
   • How much data changed while running in DR
   • The configured replication schedule
   • Any network or performance constraints
   For an 11‑TB environment, if the change rate is moderate and replication is healthy, failback can be performed as soon as the resync from DR to primary completes and monitoring shows no significant lag.

In summary, Microsoft best practice is to:

1. Use CRR with an appropriate schedule for the RPO/RTO targets.
2. On failback, perform a resync, verify replication health and lag, then cut over and remount volumes in the primary region.
3. Expect storage-side failover operations to complete in about a minute after peering is broken, with total RTO typically in the minutes-to-an-hour range for well-prepared configurations. The exact duration for 11 TB depends on change volume and environment throughput, not just raw size.

References:

• Reliability in Azure NetApp Files