Cold Storage
Low-cost archival storage for data that is rarely accessed but must be retained for compliance, backup, or historical purposes.
Also known as: Archive Storage, Cold Tier, Archival Storage, Deep Archive
Category: Concepts
Tags: storage, archival, backup, data-protection, cost-optimization
Explanation
Cold storage refers to data storage systems optimized for infrequently accessed data, offering significantly lower costs in exchange for slower retrieval times. It's a key component of tiered storage strategies and information lifecycle management, providing an economical way to retain large volumes of data long-term.
**Characteristics of cold storage**:
- **Low cost per gigabyte**: Often 5-10x cheaper than hot storage
- **Slower access times**: Minutes to hours for retrieval vs. milliseconds
- **Retrieval fees**: Some services charge per-access fees
- **Minimum storage durations**: Data may need to stay for 30-180 days
- **High durability**: Designed for long-term data integrity
**Cold storage options**:
**Cloud services**:
- AWS Glacier / Glacier Deep Archive
- Azure Archive Storage
- Google Cloud Archive Storage
- Backblaze B2 (cold tier)
**On-premises**:
- Tape libraries (LTO tapes)
- Optical media (M-DISC, archival Blu-ray)
- Offline hard drives
- Air-gapped NAS systems
**Use cases**:
- **Compliance archives**: Data required by law but rarely needed
- **Backup archives**: Long-term backup retention beyond active rotation
- **Historical records**: Past projects, old versions, legacy data
- **Media archives**: Original photos, videos, raw files
- **Legal holds**: Evidence preservation for potential litigation
**Cold storage in PKM**:
- **Old project archives**: Completed projects you might reference someday
- **Version history**: Historical snapshots of your knowledge base
- **Raw captures**: Original source materials (PDFs, books, videos)
- **Backup archives**: Monthly or yearly full backups
**Best practices**:
1. **Catalog thoroughly**: You need to find data before retrieving it
2. **Test retrieval**: Periodically verify you can actually restore data
3. **Consider retrieval costs**: Factor in access fees for planning
4. **Use appropriate formats**: Avoid proprietary formats that may become unreadable
5. **Geographic distribution**: Keep copies in multiple locations
6. **Document the archive**: Future you needs to understand what's stored and why
**Cold vs. offline vs. air-gapped**:
- **Cold storage**: Online but slow to access
- **Offline storage**: Must be physically connected to access
- **Air-gapped storage**: Never connected to networks (strongest ransomware protection)
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