Question 294 - DBS-C01 discussion

Explanation from Amazon documents:Amazon ElastiCache for Redis is a fully managed in-memory data store that supports Redis, an open source, key-value database. Amazon ElastiCache for Redis provides several features to enhance the performance, availability, scalability, and security of your Redis data, such as cluster mode, global datastore, replication groups, snapshots, and encryption.A global datastore is a feature that allows you to create a cross-Region read replica of your ElastiCache for Redis cluster. A global datastore consists of a primary cluster that is replicated across up to two other Regions as secondary clusters. A global datastore provides low-latency reads and high availability for your Redis data across Regions. A global datastore also supports encryption of cross-Region data transfers using AWS Key Management Service (AWS KMS).To create a global datastore in ElastiCache for Redis, you need to do the following:Create a primary cluster in one Region. You can use an existing cluster or create a new one. The cluster must have cluster mode enabled and use Redis engine version 5.0.6 or later.Create a global datastore and add the primary cluster to it. You can use the AWS Management Console, the AWS CLI, or the ElastiCache API to create a global datastore.Create one or two secondary clusters in other Regions and add them to the global datastore. The secondary clusters must have the same specifications as the primary cluster, such as node type, number of shards, and number of replicas per shard.Enable encryption in transit and at rest for the primary and secondary clusters. Specify a customer master key (CMK) from AWS KMS for each cluster.By creating a global datastore in ElastiCache for Redis and creating replica clusters in two other Regions, the database administrator can develop a caching solution that will be available across Regions and include low-latency replication and failover capabilities for DR. This solution will also meet the security requirement of encrypting cross-Region data transfers using AWS KMS. This solution will also require the least amount of operational effort, as it does not involve any data migration or manual intervention.Therefore, option B is the correct solution to meet the requirements. Option A is not optimal because enabling cluster mode in ElastiCache for Redis and creating multiple clusters across Regions will not provide cross-Region replication or failover capabilities. Using AWS DMS to replicate the cache data by using AWS DMS will incur additional time and cost, and may not support encryption of cross-Region data transfers. Option C is not optimal because disabling cluster mode in ElastiCache for Redis and creating multiple replication groups across Regions will not provide cross-Region replication or failover capabilities. Using AWS DMS to replicate the cache data will incur additional time and cost, and may not support encryption of cross-Region data transfers. Option D is not optimal because creating a snapshot of ElastiCache for Redis in the primary Region and copying it to the failover Region will not provide low-latency replication or high availability for the Redis data across Regions. Using the snapshot to restore the cluster from the failover Region when DR is required will involve manual intervention and downtime.