ElastiCache

Question 1

Amazon ElastiCache can be used to significantly improve latency and throughput for:

Answer 1

• Read-heavy application workloads (such as social networking, gaming, media sharing and Q&A portals)
• Compute-intensive workloads (such as a recommendation engine) by allowing you to store the objects that are often read in cache.

Question 2

Amazon ElastiCache for Redis supports

Answer 2

Advanced data structures, you can augment the database tier to provide features (such as leaderboard, counting, session and tracking) that are not easily achievable via databases in a cost-effective way.

Question 3

Why Redis instead of Memcached?

Answer 3

Redis offers
- snapshots facility
- replication
- transactions

Question 4

What is Elasticache for Redis “cluster mode”?

Answer 4

Data partitioned across up to 500 shards

Question 5

What happens to the data when you add an Elasticache for Redis read replica to a cluster?

Answer 5

• all of the data from the primary is copied to the new node.
• the changes written to the primary node are asynchronously propagated to all the read replicas.

Question 6

How do you improve fault tolerance and reduce write downtime to a Elasticache for Redis cluster?

Answer 6

Enable Multi-AZ with Automatic Failover for your Redis (cluster mode disabled) cluster with replicas.

Question 7

What happens when a Multi-AZ Elasticache for Redis (Cluster mode disabled) node fails?

Answer 7

The role of primary node will automatically fail over to one of the read replicas. There is no need to create and provision a new primary node, because ElastiCache will handle this transparently.

Question 8

Can you manually promote any of the Elasticache for Redis (Cluster mode) replica nodes to primary?

Answer 8

You cannot manually promote any of the Elasticache for Redis (Cluster mode) replica nodes to primary.