Amazon ElastiCache vs Garnet

Amazon ElastiCache is a managed caching service compatible with Valkey, Memcached, and Redis OSS, with performance described as microsecond latency. Customers can deploy a serverless cache or a node-based cluster. ElastiCache Serverless monitors compute, memory, and network use and scales vertically and horizontally as demand changes. It replicates data across multiple Availability Zones and offers a 99.99% availability SLA for each cache. Listed uses include application and semantic caching, data and session stores, and leaderboards. It can act as a front-end cache for Amazon RDS, Aurora, DocumentDB, and DynamoDB, and improve performance with EC2 and EMR. Security options include encryption in transit and at rest, IAM authentication, Valkey or Redis OSS AUTH, and role-based access control. CloudWatch provides more than 40 operational metrics at no additional charge. Valkey serverless pricing starts at $6 a month, billed according to stored data in GB-hours and requests measured in ECPUs. Data tiering is unavailable with ElastiCache Serverless.

Garnet is a free remote cache-store from Microsoft Research for self-hosted use on Linux, macOS, and Windows. It uses RESP and works with many unmodified Redis clients, including StackExchange.Redis; documented libraries also include Jedis, Redisson, redis-py, node_redis, and go-redis. Its data APIs cover strings, lists, hashes, sets, sorted sets, geo operations, HyperLogLog, bitmaps, ACLs, pub/sub, transactions, and Lua scripting. Garnet can store datasets larger than memory on local or cloud storage and supports checkpointing and recovery. Multi-node mode provides sharding, state migration, and replication. Developers can register C# data structures and read-modify-write operations through its custom operator framework. TLS/SSL and password-based RESP authentication are supported. DiskANN vector database support and Bf-Tree range indexes are marked preview. Garnet is MIT-licensed, but is not intended as a fully compatible Redis replacement and does not support Redis modules. The self-hosted plan is free; you manage infrastructure, updates, and operations. The managed Azure Cosmos DB Garnet Cache is in expanded Private Preview, with no price listed.