DatacenterDisk

MDD 18TB vs WD Ultrastar

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

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Our Recommendation
👑
WD Ultrastar DC HC550 18TB SATA

WD Ultrastar DC HC550 18TB SATA wins on both price ($17.17/TB) and warranty (5 years).

Best $/TB: WD
Best Warranty: WD
Best for RAID: WD
Full Specification Comparison
Spec
MDD
18TB SATA 7200RPM Enterprise
$21.67/TB
WD
Ultrastar DC HC550 18TB SATA
$17.17/TB
Brand
MDD
WD
Model
18TB SATA 7200RPM Enterprise
Ultrastar DC HC550 18TB SATA
Series
MDD Enterprise
Ultrastar DC
Part Number
MDD18TSATA25672E
WUH721818ALE6L4
$/TB
$21.67
👑$17.17
Price
$389.99
$309.00
Condition
New
New
Capacity
18TB
18TB
Interface
SATA-6G
SATA-6G
Form Factor
3.5"
3.5"
Drive Type
HDD
HDD
Recording Tech
CMR
ePMR
RPM
7,200
7,200
Cache
256MB
512MB
Sector Size
512e
512e
Workload Rating
👑550TB/yr
👑550TB/yr
DWPD
N/A
N/A
Warranty
👑5 years
👑5 years
Workload Tier
nearline
nearline
In Stock
✓ In Stock
✓ In Stock
Buy
Buy on Amazon →
Buy on Amazon →
Workload Fit
Workload
MDD
WD
NAS Storage
●●●
●●●
Backup Target
●●●
●●●
OLTP Database
●
●
Cold Archive
●●●
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Virtualization
●
●
AI/ML Storage
●●
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Buying Recommendation
Choose MDD 18TB SATA 7200RPM Enterprise if:
  • ✓ Your server runs 24/7 under heavy sustained load
  • ✓ You need new-with-warranty for compliance or budgeting
  • ✓ You need high-density storage for bulk/archive workloads
Buy MDD →
Choose WD Ultrastar DC HC550 18TB SATA if:
  • ✓ You need maximum storage per dollar
  • ✓ You need 5-year warranty coverage for production
  • ✓ You're building a RAID array and need guaranteed CMR compatibility
  • ✓ Your server runs 24/7 under heavy sustained load
Buy WD →

Frequently Asked Questions

WD Ultrastar offers better value at $17.17/TB vs $21.67/TB - a 21% 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 5-year warranties and are built for enterprise operation. Check brand-specific AFR data and Backblaze drive stats for real-world failure rate comparisons.

MDD 18TB 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.