Backup vs Archive

The terms “backup” and “archive” are often used interchangeably, but they serve fundamentally different purposes. Confusing them leads to poor data management: either paying too much for storage, losing data that should have been preserved, or failing to recover when disaster strikes. Understanding the distinction is essential for designing a sound data protection strategy.

Key Differences

flowchart LR
    subgraph backup["Backup"]
        direction TB
        B1["Active data copy"]
        B2["Short-to-medium retention"]
        B3["Fast restore"]
        B4["Disaster recovery"]
    end

    subgraph archive["Archive"]
        direction TB
        A1["Inactive data moved"]
        A2["Long-term retention"]
        A3["Infrequent access"]
        A4["Compliance and history"]
    end

    DATA["Production Data"] -->|"Copy"| backup
    DATA -->|"Move"| archive

When to Use Backups

Backups protect active data against loss from hardware failure, ransomware, human error, or software bugs. The goal is to restore production systems to a recent known-good state as quickly as possible.

Use backups for:

• Production databases and application data
• Configuration files and infrastructure definitions
• Active project files and source code repositories
• Email and collaboration platforms in active use
• Any data where losing recent changes would disrupt operations

Backup characteristics:

• Frequency matters: the interval between backups defines your maximum data loss (RPO)
• Speed matters: restore time defines your downtime (RTO)
• Versions expire: older backups are pruned according to a retention policy
• Data stays active: the original remains in production, the backup is a safety net

When to Use Archives

Archives preserve data that is no longer actively used but must be retained for legal, regulatory, or historical reasons. Archiving also reduces production storage costs by moving cold data to cheaper, denser media.

Use archives for:

• Completed project files that must be retained but are no longer modified
• Financial records required by law for a specific number of years
• Email and communication records subject to regulatory retention
• Log files older than the active analysis window
• Decommissioned system images and database exports
• Research data and datasets that support published results

Archive characteristics:

• Integrity matters: archived data must remain bit-for-bit identical to the original over its entire retention period
• Cost matters: archived data may be stored for decades, so per-TB cost is critical
• Access is rare: retrieval may take hours (tape, Glacier Deep Archive) and that is acceptable
• Immutability matters: archives should be write-once to prevent tampering or accidental modification
• Metadata matters: data is useless if it cannot be found; archives need structured indexing

Common Mistakes

Using backups as archives: backup retention policies prune old data. If the only copy of a completed project exists in a backup with a 90-day retention window, it will be automatically deleted after 90 days. Data that must be retained long-term needs to be explicitly archived, not left in a backup rotation.

Using archives as backups: archives are optimized for cost and durability, not speed. Restoring a production database from Glacier Deep Archive takes hours and incurs significant retrieval costs. Active data needs backups on fast storage with short recovery times.

Archiving without metadata: dumping files into a storage bucket without a catalog or naming convention makes them effectively lost. Years later, no one knows what the data is, why it was saved, or whether it can be deleted. Every archive entry needs at minimum: description, creation date, retention period, owner, and the regulatory or business reason for retention.

Never deleting archives: retaining data indefinitely increases storage costs and legal exposure. Data that has passed its required retention period should be reviewed and deleted. Holding data longer than necessary can create liability during legal discovery.

Archiving encrypted data without key management: if the encryption key is lost, the archived data is permanently unreadable. Archive the decryption keys alongside the data or in a dedicated key management system, and verify decryption periodically over the archive’s lifetime.

Ignoring format obsolescence: data archived in proprietary formats may become unreadable when the software that created it is no longer available. Prefer open, well-documented formats (PDF/A, CSV, plain text, open image formats) for long-term archival storage.

Backup and Archive Together

Backups and archives are complementary, not interchangeable. A complete data protection strategy uses both:

• Backups handle operational recovery: “restore yesterday’s database”
• Archives handle long-term preservation: “retrieve the 2019 audit records”

Neither replaces the other. A system with only backups will lose historical data when retention windows expire. A system with only archives will have no way to quickly recover from a production failure.

The practical approach:

1. Back up active data according to RPO/RTO requirements
2. When data becomes inactive, archive it with proper metadata and retention tags
3. Apply retention policies to both: prune old backups, review and delete expired archives
4. Test both: verify backup restores and archive retrievals regularly

Summary

Backups are copies of active data for fast recovery. Archives are preserved inactive data for long-term retention. Using one where the other is needed leads to either data loss or unnecessary cost. Design your strategy around both, with clear policies for when data transitions from one to the other.