To achieve the fastest failover in storage replication, which option is typically used despite higher bandwidth requirements?

• A. Asynchronous
• B. Synchronous
• C. Tape-based
• D. Mirrored-at-rest

Answer: (B)

Synchronous replication is the approach that enables the fastest failover because it writes data to both the primary and remote storage as part of the same transaction and waits for acknowledgments from the remote site before completing the write. This keeps the two copies in lockstep, so when a failover occurs, the secondary site already contains the most recent data, minimizing data loss (often zero data loss, or an RPO of zero) and making the switch seamless. The catch is that it demands a high-bandwidth, low-latency network, since every write must be transmitted and confirmed across the network before the operation can finish. If the network cannot support that level of performance, latency increases and throughput suffers, which is why some environments opt for asynchronous replication, even though it can incur data loss in a failover. Tape-based backups and data mirrored only at rest do not provide real-time, up-to-date copies for rapid failover.