What is the best option for implementing a secondary datacenter for failover without affecting the WAN link during production hours?

Asynchronous replication is the most effective option for implementing a secondary datacenter for failover without impacting the WAN link during production hours. This method allows data to be copied from the primary site to the secondary site with a delay, rather than in real-time.

In asynchronous replication, changes made to the data at the primary site are queued and then sent to the secondary site at intervals. This is particularly beneficial during production hours, as it minimizes the load on the WAN link, allowing normal operations to continue without disruption. The delay in replication can be acceptable in many scenarios, especially if the secondary datacenter is used primarily for disaster recovery purposes.

While other options, such as site mirroring, provide real-time replication, they can create significant traffic on the WAN, potentially affecting performance. Storage deduplication is primarily a data reduction technique and does not address the WAN impact directly. Cold site failover with offsite archiving may not provide the immediate availability needed for critical applications, as this approach relies on manual recovery processes and would involve increased downtime. Therefore, asynchronous replication stands out as the optimal choice in this context for ensuring minimal impact on WAN resources during production.