The requirement for the database to be accessible during a datacenter failure necessitates configuring zone-redundant high availability (HA). In Azure Database for MySQL Flexible Server, zone-redundant HA is supported only on the General Purpose and Memory Optimized compute tiers. The Burstable tier does not support this feature.

Between the General Purpose and Memory Optimized tiers, the General Purpose tier offers a balanced ratio of compute, memory, and storage, making it suitable for most production workloads at a lower price point than the Memory Optimized tier. To meet the requirement of minimizing costs while ensuring high availability, the General Purpose tier is the most appropriate recommendation.

A. Burstable: This tier does not support zone-redundant high availability, which is required to ensure the database is accessible if an entire datacenter (Availability Zone) fails.

C. Memory Optimized: While this tier supports zone-redundant high availability, it is more expensive than the General Purpose tier. It does not meet the requirement to minimize costs.

1. Microsoft Learn: High availability concepts in Azure Database for MySQL - Flexible Server. Under the "Zone-redundant high availability" section

it states

"Zone-redundant high availability is available for the General Purpose and Memory Optimized compute tiers. It is not supported in the Burstable compute tier."

2. Microsoft Learn: Compute and storage options in Azure Database for MySQL - Flexible Server. This document details the different compute tiers. The "When to choose this tier" section for General Purpose indicates it is for "most business workloads

" while Memory Optimized is for "high-performance database workloads." This implies a cost and performance hierarchy where General Purpose is the more cost-effective baseline for production HA.