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Security+ Academy · Lesson

Backup Strategies: 3-2-1 Rule and Immutable Backups

Implement the 3-2-1 backup rule (3 copies, 2 media types, 1 offsite) and immutable backups that ransomware cannot encrypt or delete.

Why Backups Are a Security Control

Backups are not just an IT operational concern — they are a critical security control that directly enables recovery from ransomware, accidental deletion, hardware failure, and insider sabotage. Without tested, reliable backups, ransomware operators hold all the power: pay or lose your data. With robust, protected backups, organizations can recover without paying ransom. The Security+ exam explicitly includes backup strategy as part of business continuity and data protection requirements.

The 3-2-1 Backup Rule

The 3-2-1 backup rule is the industry-standard baseline for backup resilience. 3 copies of data must exist (original + 2 backups). 2 different storage media types must be used (e.g., local disk and tape, or local NAS and cloud). 1 copy must be stored offsite or in a geographically separate location. This configuration ensures that no single failure — disk failure, site disaster, theft — eliminates all copies of the data. The 3-2-1 rule has been the backup gold standard for two decades.

# 3-2-1 backup rule example:
# Copy 1 (primary): Production database server
#   Location: Primary data center, local SSD

# Copy 2 (local backup): Backup appliance
#   Media: Network-attached storage (different media type)
#   Location: Same data center (different failure domain)

# Copy 3 (offsite backup): Cloud storage
#   Media: Cloud object storage (S3, Azure Blob)
#   Location: Different geographic region (offsite)

# Single failure scenarios that DON'T lose all copies:
# - Production disk fails -> 2 copies remain
# - Data center flood -> offsite cloud copy survives
# - Local NAS failure -> production + cloud remain

All lessons in this course

  1. BCP vs DRP: Planning for Disruption and Recovery
  2. RTO, RPO, and MTTR: Defining Recovery Objectives
  3. Backup Strategies: 3-2-1 Rule and Immutable Backups
  4. Failover Testing: Tabletop Exercises and DR Drills
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