RTO Recovery Time Objective and RPO Recovery Point Objective setup

Setting Up RTO and RPO for Critical Systems

RTO (Recovery Time Objective) — maximum acceptable downtime after failure. RPO (Recovery Point Objective) — maximum acceptable data loss in time units. These two parameters determine entire backup architecture: lower values mean more expensive infrastructure.

Cost dependency on RTO/RPO

Determine business requirements

# Calculate downtime cost to define acceptable RTO
class RtoCalculator:
    def calculate_downtime_cost(
        self,
        hourly_revenue: float,
        customer_churn_per_hour: float,
        penalty_per_sla_violation: float,
        avg_customer_lifetime_value: float,
        total_customers: int
    ) -> dict:

        costs_per_hour = {
            'lost_revenue': hourly_revenue,
            'customer_churn': (customer_churn_per_hour / 100) * total_customers
                             * avg_customer_lifetime_value,
            'sla_penalties': penalty_per_sla_violation,
            'recovery_labor': 500
        }

        total_per_hour = sum(costs_per_hour.values())

        return {
            'cost_per_hour': total_per_hour,
            'recommended_rto': self._recommend_rto(total_per_hour),
        }

PostgreSQL configuration for RPO = 5 minutes

# postgresql.conf — WAL archiving for PITR
wal_level = replica
archive_mode = on
archive_command = 'pgbackrest --stanza=main archive-push %p'

# Checkpoint frequency
checkpoint_timeout = 5min

Patroni: automatic failover (RTO < 30 sec)

# /etc/patroni/patroni.yml
scope: postgres-cluster
namespace: /service/
name: pg-node-1

bootstrap:
  dcs:
    ttl: 30               # failover after 30s without heartbeat
    maximum_lag_on_failover: 1048576

  postgresql:
    parameters:
      wal_level: replica
      hot_standby: on
      max_wal_senders: 10
      archive_mode: on
      archive_command: 'pgbackrest --stanza=main archive-push %p'

HAProxy: routing by role

# haproxy.cfg
frontend postgres_write
  bind *:5432
  default_backend postgres_primary

backend postgres_primary
  option httpchk GET /master
  http-check expect status 200
  server pg-node-1 pg-node-1-ip:5432 check port 8008
  server pg-node-2 pg-node-2-ip:5432 check port 8008
  server pg-node-3 pg-node-3-ip:5432 check port 8008

frontend postgres_read
  bind *:5433
  default_backend postgres_replicas

backend postgres_replicas
  balance roundrobin
  option httpchk GET /replica
  http-check expect status 200
  server pg-node-1 pg-node-1-ip:5432 check port 8008
  server pg-node-2 pg-node-2-ip:5432 check port 8008
  server pg-node-3 pg-node-3-ip:5432 check port 8008

Monitoring RTO/RPO metrics

# Prometheus alerting for SLA violations
- alert: ReplicationLagCritical
  expr: postgresql_replication_lag_seconds > 300
  for: 2m
  labels:
    severity: critical
  annotations:
    summary: "RPO at risk: replica lag {{ $value }}s > 5min RPO target"

Timeline

Setup of Patroni + pgBackRest + HAProxy to achieve RTO < 30 min and RPO < 5 min — 3–5 business days.