Price per TB: HDDs still dominate
**External HDD:** • 4TB: $60–$80 ($15–$20 per TB) • 8TB: $100–$130 ($12–$16 per TB) • 12TB: $150–$180 ($12–$15 per TB) **External SSD:** • 1TB: $100–$130 ($100–$130 per TB) • 2TB: $200–$250 ($100–$125 per TB) • 4TB: $400–$500 ($100–$125 per TB) HDDs are 6–10× cheaper per TB. For archival storage (photo libraries, video archives, cold backups), HDDs are unbeatable on cost.
Speed: SSDs win decisively
**External HDD**: 100–150 MB/s sustained. Copying a 100GB file: ~15 minutes **External SSD (USB 3.1)**: 400–1,050 MB/s. Same file: 2–5 minutes **External SSD (USB 3.2 Gen 2x2)**: 1,000–2,000 MB/s. Same file: 1–3 minutes For active workflow (daily backups, frequent file access), SSD speed cuts backup time significantly. For set-it-and-forget-it archival, HDD is fine.
Durability & reliability
**External HDD:** • Mechanical failure risk after 3–5 years • Sensitive to drops and impacts (moving parts) • Heat reduces lifespan • MTBF: 750,000 hours (~85 years) on paper, ~5–7 years real-world **External SSD:** • No moving parts (highly drop-resistant) • Immune to vibration and shock • Write-limited (1,000–3,000 TBW), but takes decades to hit on backups • MTBF: Typically 2+ million hours, practical lifespan 10+ years For critical data, SSD is more reliable. For long-term archival (10+ years), either is fine if stored properly (cool, dry place).
What to buy: storage strategy
**Active backup (daily/weekly syncs)**: External SSD (1TB–2TB). Speed matters. Samsung T7 or SanDisk Extreme V2. **Bulk archival (photos, finished projects)**: External HDD (8TB–12TB). Cost matters. WD My Book or Seagate Backup Plus. **Hybrid setup (recommended)**: 2TB external SSD for active backups + 8TB external HDD for cold storage. Best of both: speed + capacity at reasonable cost.