You are migrating a business critical application from your local data center into Google Cloud. As part of your high-availability strategy, you want to ensure that any data used by the application will be immediately available if a zonal failure occurs. What should you do?

Regional persistent disks are designed for high availability by synchronously replicating data between two zones within the same region. If the primary zone containing the virtual machine (VM) fails, the application can be failed over to the other zone. You can force-attach the regional persistent disk to a new VM instance in the secondary zone. This process ensures that the data is immediately available with minimal downtime, which is critical for a business-critical application as specified in the scenario.

A. Zonal persistent disks are confined to a single zone. If that zone fails, the disk becomes inaccessible. Restoring from a snapshot introduces latency and potential data loss (RPO), failing the "immediately available" requirement.
B. A zonal persistent disk cannot be attached to a VM in a different zone. This action is technically impossible, making it an invalid solution for a zonal failure.
C. While using the correct disk type (regional), the recovery process is flawed. Restoring from a snapshot is unnecessary and slow; the primary benefit of a regional disk is its immediate availability in the failover zone.

1. Google Cloud Documentation, "High availability with regional persistent disks": "Regional persistent disks provide synchronous replication of data between two zones in a region. ... If your primary zone becomes unavailable, you can fail over to your secondary zone. In the secondary zone, you can force-attach the regional persistent disk to a new VM instance." (See section: "Failing over your regional persistent disk").

2. Google Cloud Documentation, "About persistent disk snapshots": "Snapshots are global resources... Use snapshots to protect your data from unexpected failures... Creating a new persistent disk from a snapshot takes time..." This highlights that snapshots are for disaster recovery/backups, not instantaneous high-availability failover.

3. Google Cloud Documentation, "Persistent disk types": "Zonal persistent disks are located in a single zone. If a zone becomes unavailable, all zonal persistent disks in that zone are unavailable until the zone is restored." This confirms that options A and B are unsuitable for zonal failure scenarios.