Son, Father, Grandfather (SFG) Retention Strategy

Introduction

The Son, Father, Grandfather (SFG) strategy is a standard industry approach to balance frequent backups with long-term storage efficiency:

Son (Daily): Keeps the most recent snapshots from the last 7 days.
Father (Weekly): Keeps the Monday snapshot from the previous 4 weeks.
Grandfather (Monthly): Keeps the snapshot taken on the 23rd of each month for the last 12 months.

This layered structure ensures both short-term recovery and long-term archiving.

Scheduler Configuration

Frequency: Snapshots are taken daily at 01:00 AM GMT+12.
Retention Rules: - 7 daily snapshots (Son) - 4 weekly snapshots (Father – every Monday) - 12 monthly snapshots (Grandfather – 23rd of each month)

Snapshot Timeline (1 Year)

After one year, you will retain:

7 daily snapshots
4 weekly snapshots (Mondays)
12 monthly snapshots (23rd of each month)

Total retained snapshots after 1 year:

7 + 4 + 12 = 23 snapshots

All older snapshots are automatically deleted based on the rules.

API Summary

Create the Snapshot Policy

Endpoint:

POST /api/2.0/backupschedulers/

JSON Payload:

{
  "type": "snapshot",
  "name": "Son, Father, GrandFather Policy",
  "enable_backup_policy_notifications": true,
  "enable_retention_policy_notifications": false,
  "is_enabled": true,
  "is_default": false,
  "manual_incremental_backup": "",
  "retention_policy": {
    "name": "Son, Father, GrandFather Policy",
    "rules": [
      { "period": "days", "quantity": 7 },
      { "period": "weeks", "quantity": 4, "time_option": 1 },
      { "period": "months", "quantity": 12, "time_option": 23 }
    ]
  },
  "initial_backup": {
    "day_of_week": ["*"],
    "start_time": { "hour": 12, "minute": 0 },
    "end_time": { "hour": 11, "minute": 45 }
  },
  "incremental_backup": {
    "day_of_month": "*",
    "day_of_week": ["*"],
    "month": "*",
    "hour": "1",
    "minute": "0",
    "repeat": { "hour": "", "minute": "" },
    "start_time": { "hour": 12, "minute": 0 },
    "end_time": { "hour": 11, "minute": 45 }
  },
  "user_timezone": "Etc/GMT+12"
}