Amazon ElastiCache - Notes - 02 - Memcached

AWS > Database > Amazon ElastiCache:

Notes:
1. A Memcached node is the smallest building block of an ElastiCache deployment.
2. A Memcached cluster is a logical grouping of one or more ElastiCache Nodes. Data is partitioned across the nodes in a Memcached cluster.
3. It is not persistent
    3A. It can not be used as a data store.
    3B. If the node fails, the cached data(in the node) is lost.
4. Ideal front-end for data stores(RDS, DynamoDB.. etc.)

Features:
1. It can integrate with SNS for node failure/recovery notification.
2. Support auto discovery for nodes added/removed from the Memcached cluster.
3. Scales out/in(Horizontally) by adding/removing cluster nodes.
4. Scales up/down(Vertically) by changing node family/type.
    4A. Since it is not persistent, scaling up/down involves creating a new cluster.
    4B. The new cluster start empty without data unless your application populates it.
5. It does not support Multi-AZ failover, replication, Snapshots for backup/restore.
    5A. Node failure means data loss.
6. You can place your Memcached nodes in different AZs to minimize the impact of an AZ failure and to contain the data loss in such an incident.

Memcached Use Cases:
1. Cache contents of DB.
2. Cache data from dynamically generated webpages
3. Transient session data
4. High frequency counters for admission control in high volume web Apps.


Reference:
1. AWS Documentation - What Is Amazon ElastiCache for Memcached?
https://docs.aws.amazon.com/AmazonElastiCache/latest/mem-ug/WhatIs.html


最初發表 / 最後更新: 2020.06.08 / 2020.06.08