redis.clients.connected_slaves

When Redis disconnects slow clients that can't keep up with output buffer, redis.clients.connected drops suddenly. This is often caused by clients with slow network connections or blocking on their end, especially for pub/sub subscribers or replicas.

When redis.replication.repl_backlog_size is too small relative to write rate and network latency, replicas require full resync after brief disconnections, causing replication storms and increased master load.