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Seagate IronWolf vs WD Ultrastar

Side-by-side spec and price comparison. Live data from Amazon US.

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Our Recommendation
👑
Seagate IronWolf 4TB NAS

Seagate IronWolf 4TB NAS offers the best value at $25.00/TB. Available new with manufacturer warranty.

Best $/TB: Seagate
Best Warranty: Seagate
Best for RAID: Seagate
Full Specification Comparison
Spec
Seagate
IronWolf 4TB NAS
$25.00/TB
WD
Ultrastar 7K4000 4TB SATA NAS
$36.25/TB
Brand
Seagate
WD
Model
IronWolf 4TB NAS
Ultrastar 7K4000 4TB SATA NAS
Series
IronWolf
Ultrastar
Part Number
ST4000VN006
HMS5C4040ALE640
$/TB
👑$25.00
$36.25
Price
$99.99
$145.00
Condition
New
New
Capacity
4TB
4TB
Interface
SATA-6G
SATA-6G
Form Factor
3.5"
3.5"
Drive Type
HDD
HDD
Recording Tech
CMR
CMR
RPM
5,400
7,200
Cache
256MB
—
Sector Size
512e
512n
Workload Rating
180TB/yr
—
DWPD
N/A
N/A
Warranty
3 years
—
Workload Tier
nearline
nearline
In Stock
✓ In Stock
✓ In Stock
Buy
Buy on Amazon →
Buy on Amazon →
Workload Fit
Workload
Seagate
WD
NAS Storage
●●●
●●●
Backup Target
●●●
●●●
OLTP Database
●
●
Cold Archive
●
●
Virtualization
●
●
AI/ML Storage
●
●
Buying Recommendation
Choose Seagate IronWolf 4TB NAS if:
  • ✓ You need maximum storage per dollar
  • ✓ You need 3-year warranty coverage for production
  • ✓ You're building a RAID array and need guaranteed CMR compatibility
  • ✓ You need new-with-warranty for compliance or budgeting
Buy Seagate →
Choose WD Ultrastar 7K4000 4TB SATA NAS if:
  • ✓ You need new-with-warranty for compliance or budgeting
Buy WD →

Frequently Asked Questions

Seagate IronWolf offers better value at $25.00/TB vs $36.25/TB - a 31% price difference. Factor in warranty length and workload rating when the price gap is small.

Mixing drives of different models in RAID is not recommended even if capacities match. Different firmware, error handling and seek patterns can cause rebuild issues. Use identical drives within the same RAID group for reliable operation.

Seagate IronWolf carries a longer 3-year warranty vs unknown years for WD Ultrastar. Longer warranty typically correlates with manufacturer confidence in reliability.

Seagate IronWolf is the better fit for NAS storage. It uses CMR recording which is safe for all RAID levels. SATA interface is compatible with all NAS platforms including Synology, QNAP and TrueNAS.

Seagate IronWolf vs WD Ultrastar - Comparison | DatacenterDisk