Verdict

For a NAS or any RAID array, the WD30EFZX is the clear pick - it's a CMR drive, while the ST3000DM007 uses SMR recording, which is not recommended for RAID. Only consider the ST3000DM007 for single-drive or archival use.

ST3000DM007 WD30EFZX
Capacity 3 TB 3 TB
Recording tech SMR CMR
RAID / NAS safe No Yes
Class Desktop NAS
Spindle speed 5400 RPM 5400 RPM
Cache 256 MB 128 MB
Noise (idle) 22 dB 24 dB
Fill Air Air
Interface SATA SATA
Failure rate (AFR) - -
Price / TB $56.88 $68.76

Highlighted cells mark the stronger spec for a NAS build. Failure rates from Backblaze Drive Stats where available; $/TB shows once live prices are wired.