Support On-Disk Backend Storage for ClickHouse-Keeper

Why it matters

This feature adds the capability for clickhouse-keeper to use on-disk storage instead of only in-memory storage. It improves data durability and crash recovery by persisting keeper state to disk, thus enhancing reliability and reducing data loss risk during restarts or failures.

How to use it

To enable on-disk storage for clickhouse-keeper, configure the keeper’s settings to specify a data directory for persistent storage. This typically involves setting the storage_path parameter in the clickhouse-keeper configuration file. After configuration, clickhouse-keeper will maintain its state on disk automatically.