Logical replication slot retained 180 GB of WAL causing disk pressure

A logical replication slot retained 180 GB of WAL after a DDL mismatch, causing disk usage to cross 85% before detection. Inactive or stalled logical replication slots prevent WAL cleanup, leading to disk exhaustion.

Monitor logical replication slot status regularly. Check replication_slot_restart_delay_bytes and replication_slot_wal_status metrics. Drop inactive slots immediately. Investigate DDL mismatches between publisher and subscriber. Set disk space alerts well below 85% usage.