DatacenterDisk

WD Ultrastar vs WD WD

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

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Our Recommendation
👑
WD Ultrastar 4TB SATA

WD Ultrastar 4TB SATA offers the best value at $32.50/TB. As a refurb unit, verify SMART data on arrival.

Best $/TB: WD
Best Warranty: WD
Best for RAID: WD
Full Specification Comparison
Spec
WD
Ultrastar 4TB SATA
$32.50/TB
WD
WD Purple 4TB WD40PURX
$55.25/TB
Brand
WD
WD
Model
Ultrastar 4TB SATA
WD Purple 4TB WD40PURX
Series
Ultrastar HC310
WD Purple
Part Number
—
WD40PURX
$/TB
👑$32.50
$55.25
Price
$129.99
$221.00
Condition
Refurb
New
Capacity
4TB
4TB
Interface
SATA-6G
SATA-6G
Form Factor
3.5"
3.5"
Drive Type
HDD
HDD
Recording Tech
CMR
—
RPM
7,200
N/A (SSD)
Cache
256MB
—
Sector Size
—
—
Workload Rating
—
—
DWPD
N/A
N/A
Warranty
—
—
Workload Tier
nearline
—
In Stock
✓ In Stock
✓ In Stock
Buy
Buy on Amazon →
Buy on Amazon →
Workload Fit
Workload
WD
WD
NAS Storage
●●●
●●●
Backup Target
●●●
●●●
OLTP Database
●
●
Cold Archive
●
●
Virtualization
●
●
AI/ML Storage
●
●
Buying Recommendation
Choose WD Ultrastar 4TB SATA if:
  • ✓ You need maximum storage per dollar
  • ✓ You're building a RAID array and need guaranteed CMR compatibility
  • ✓ You're comfortable with datacenter refurb to maximize savings
Buy WD →
Choose WD WD Purple 4TB WD40PURX if:
  • ✓ You need new-with-warranty for compliance or budgeting
Buy WD →

Frequently Asked Questions

WD Ultrastar offers better value at $32.50/TB vs $55.25/TB - a 41% 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.

Both drives carry similar warranty terms and are built for enterprise operation. Check brand-specific AFR data and Backblaze drive stats for real-world failure rate comparisons.

WD Ultrastar 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.