What should you configure to ensure a hypervisor can boot after an OS disk crash?

To ensure a hypervisor can boot after an OS disk crash, configuring RAID 1 is the most effective approach. RAID 1, also known as disk mirroring, duplicates the data across two or more disks. This mirroring allows for redundancy; if one disk fails, the system can continue to operate using the other disk(s) without data loss or downtime.

In the context of a hypervisor, which is critical for hosting virtual machines, maintaining availability is paramount. By implementing RAID 1, the hypervisor's operating system is secured against a single point of failure. Should the primary OS disk experience a crash, the hypervisor can seamlessly boot from the mirrored disk, ensuring that virtual machines remain accessible.

RAID 0, while it enhances performance by striping data across multiple disks, does not provide any redundancy; therefore, a failure in one disk results in the loss of all data. Enabling a failover cluster and synchronous replication are strategies aimed at overall system availability and disaster recovery, but they do not directly address the immediate need for the hypervisor's boot capability in the event of an OS disk crash. Thus, RAID 1 is the best choice for achieving the desired outcome.