Is ElastiCache Redis cluster?
ElastiCache allows you to quickly and easily launch a new Redis cluster using the AWS Management Console, CLI, or SDKs. You can also select an engine version, though we generally recommend using the latest available version of the Redis engine. We can also specify the number of shards and replicas per shard.
Is ElastiCache the same as Redis?
ElastiCache improves the performance of web applications by allowing you to retrieve information from fast, managed, in-memory caches, instead of relying entirely on slower disk-based databases. On the other hand, Redis is detailed as “An in-memory database that persists on disk”.
How long is Redis failover?
In Redis Cluster, when a primary node fails, the Redis cluster detects the failure and promotes a replica node to be the new primary for the shard. The cluster informs all nodes in the cluster and all clients about the change. This process should usually take about 30 seconds.
What is the benefit of enabling multi-AZ with auto failover in ElastiCache Redis?
Enabling the Multi-AZ Automatic Failover feature for your Redis Cache clusters will improve the fault tolerance in case the read/write primary node becomes unreachable due to loss of network connectivity, loss of availability in the primary’s AZ, etc.
What is ElastiCache cluster?
Clusters. The basic building block of ElastiCache for Redis is the cluster. A cluster is a collection of one or more cache nodes, all of which run an instance of the Redis cache engine software. When you create a cluster, you specify the engine and version for all of the nodes to use.
What is Redis failover?
How Redis offers High Availability and Automatic Failover? Redis sentinel is the high availability solution offered by Redis. In case of a failure in your Redis cluster, Sentinel will automatically detects the point of failure and bring the cluster back to stable mode without any human intervention.
Is ElastiCache scalable?
By using Amazon ElastiCache you can scale to meet current demand, paying only for what you use. ElastiCache enables you to scale your cache to match demand.
What is the purpose of ElastiCache?
According to the Amazon website, ElastiCache makes it easy to deploy, operate, and scale an in-memory cache in the cloud. The service improves the performance of web applications by enabling information retrieval from a fast, managed, in-memory caching system, instead of relying entirely on slower disk-based databases.
Is Redis Cluster single-threaded?
Redis is, mostly, a single-threaded server from the POV of commands execution (actually modern versions of Redis use threads for different things). It is not designed to benefit from multiple CPU cores.
When creating an Amazon ElastiCache Redis cluster What is the difference between disabling and enabling cluster mode?
A Redis (cluster mode disabled) cluster always has a single shard (API/CLI: node group) with up to 5 read replica nodes. A Redis (cluster mode enabled) cluster has up to 500 shards with 1 to 5 read replica nodes in each.
What is multi AZ in ElastiCache?
When Multi-AZ is enabled, ElastiCache continually monitors the state of the primary node. If the primary node fails, one of the following actions is performed depending on the type of failure. Topics. Failure scenarios when only the primary node fails. Failure scenarios when the primary node and some read replicas fail.
What is Redis cluster mode?
Redis (cluster mode enabled) supports partitioning your data across up to 500 node groups. You can dynamically change the number of shards as your business needs change. One advantage of partitioning is that you spread your load over a greater number of endpoints, which reduces access bottlenecks during peak demand.
What is an Amazon ElastiCache for Redis cluster?
An Amazon ElastiCache for Redis cluster is a collection of one or more Amazon ElastiCache for Redis nodes; the primary node will be in the primary cluster and the read replica node will be in a read replica cluster. A cluster manages a logical key space, where each node is responsible for a part of the key space.
How do I enable Multi-AZ on my Redis cluster?
You can enable Multi-AZ using the ElastiCache Management Console, the AWS CLI, or the ElastiCache API. Enabling ElastiCache Multi-AZ on your Redis cluster (in the API and CLI, replication group) improves your fault tolerance.
Is Redis Multi-AZ with automatic failover supported on T1 nodes?
Multi-AZ with Automatic Failover is supported on Redis version 2.8.6 and later. Redis Multi-AZ with Automatic Failover is not supported on T1 node types. Redis replication is asynchronous. Therefore, when a primary cluster fails over to a replica, a small amount of data might be lost due to replication lag.
What is non-Redis cluster mode?
Non-Redis Cluster mode: Use the primary endpoint for all write traffic. During any configuration changes or failovers, Amazon ElastiCache ensures that the DNS of the primary endpoint is updated to always point to the primary node. Use the reader endpoint to direct all read traffic.