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AWS’ new MemoryDB also seems to be a strongly consistent Redis cluster service. Anyone know how they compare? https://aws.amazon.com/memorydb/features/ https:/

• deleted 3y ago
  [deleted]
• kbumsik 3y ago
  MemoryDB has a single node (primary node) strong consistency. MemoryDB seems to have a very similar architecture to that of AWS Aurora, which separates a storage layer and compute nodes and consistency is implemented not by communicating between compute nodes but by offering a consistent distributed storage layer. This architecture usually don't have a multi-node strong consistency by itself and can have replicas. This means that in MemoryDB only the primary node is strongly consistent but the replica nodes don't. Instead, in my experience, those kinds of AWS offerings have less operational headaches because the storage remains safe even the primary node fails and you don't need to worry about managing distributed nodes. Edit: add pros
• phamilton 3y ago
  My understanding of MemoryDB is that it basically replaces the AOF with a distributed log (it might be Kafka/kinesis, but it could just be backed by the same data layer as aurora). The biggest win there is that acknowledged writes are not lost if the writer node dies. A reader can replay the log and get fully caught up as it is promoted during a failover. This comes at a cost though and writes are slower than traditional redis.