Verdict

These are comparable SSDs. The ZA4000NM1A002 is rated for the most write endurance, so it lasts longest in a NAS that sees steady writes; for light use any is fine and price decides.

WDS400T2X0E
WD Black SN850X · 4TB · Desktop
No DE price yet
ZA4000NM1A002
Seagate IronWolf 125 · 4TB · NAS
No DE price yet

Value at a glance

Endurance (TBW)
WDS400T2X0E 2,400 TB
ZA4000NM1A002 5,600 TB

Price history

DE · cheapest per day

WDS400T2X0E €837
zoomed · drag to zoom
€1,781 €1,061 €342 Nov 2024 Mar 2025 Aug 2025 Dec 2025 May 2026 Sep 2026
WDS400T2X0E ZA4000NM1A002
Capacity 4 TB 4 TB
Form factor M.2 2.5
Interface NVMe SATA
NAND type TLC TLC
Endurance (TBW) 2,400 TB 5,600 TB
DWPD - 0.7
DRAM cache Yes Yes
Power-loss protection No No
Sustained write - -
Cost / TBW $0.329 -
Price / TB $197.50 -
Buy No DE price yet No DE price yet

Highlighted cells mark the stronger spec for a NAS build. Failure rates from Backblaze Drive Stats where available; $/TB uses the cheapest live price. Buy links are Amazon affiliate.

WDS400T2X0E

No Backblaze failure data for this model.

ZA4000NM1A002

No Backblaze failure data for this model.