etcd vs RonDB

etcd is an open-source, strongly consistent distributed key-value store for data used by distributed systems and clusters of machines. It arranges values in hierarchical directories and lets clients watch keys or directories for changes. Clients can read and write values with standard HTTP tools such as curl, and keys may have optional time-to-live expiration. The project uses the Raft protocol and handles leader elections during network partitions, including when a leader machine fails. etcd is a core Kubernetes component and its primary datastore. The project provides pre-built binaries, source builds, and container images. Linux on AMD64 and ARM64 is tier 1; Darwin and Windows on either architecture are tier 3, and other platforms are unsupported. TLS and client-certificate authentication are supported for client and peer connections, but neither is enabled by default. The software is self-hosted and licensed under Apache 2.0, with a listed price of free. The integrations listing includes Kubernetes, CoreDNS, and language client libraries, while warning that third-party tools and libraries there are not tested or maintained by the etcd team.

RonDB is an open-source distributed storage engine for real-time applications and a fork of MySQL NDB Cluster. Its shared-nothing design supports up to 1 PiB of storage, with online horizontal and vertical scaling for storage and MySQL-server compute. Applications can use the MySQL Server API for SQL-compatible access and parallel queries. ACID transactions are provided through MySQL-server support; in-memory data is persisted using REDO logs and checkpoints.

RonDB describes its performance aims as low latency, high availability, high throughput, and scalable storage. It supports AI application storage integrated with Spark and Kafka, while Rondis implements a Redis server using RonDB storage and the Redis wire protocol. Deployment options include local testing, Docker, cloud deployments using your own AWS, Azure, or GCP credentials, and on-premises deployment by inquiry. Replication can be synchronous active-active across availability zones or asynchronous across regions with conflict resolution. RonDB is used as the online feature-store database for machine-learning applications in Hopsworks. The serverless plan through Hopsworks is free, with quotas on Feature Groups and memory usage.