Verdict

These are comparable SSDs. The WDS400T2R0A 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.

WDS400T2R0A
WD Red SA500 · 4TB · NAS
$1,276 ($319.03/TB)
WDS400T4X0E
WD Black SN7100 · 4TB · Desktop
$610 ($152.50/TB)

Value at a glance

Price / TB
WDS400T2R0A $232.20
WDS400T4X0E $150.46
Endurance (TBW)
WDS400T2R0A 2,500 TB
WDS400T4X0E 2,400 TB

Price history

US · cheapest per day

WDS400T2R0A $1,276 WDS400T4X0E $610
zoomed · drag to zoom
$1,562 $886 $210 Nov 2024 Mar 2025 Aug 2025 Jan 2026 Jun 2026 Nov 2026
WDS400T2R0A WDS400T4X0E
Capacity 4 TB 4 TB
Form factor 2.5 M.2
Interface SATA NVMe
NAND type TLC TLC
Endurance (TBW) 2,500 TB 2,400 TB
DWPD - -
DRAM cache Yes No
Power-loss protection No No
Sustained write - -
Cost / TBW $0.372 $0.251
Price / TB $232.20 $150.46
Buy
$1,276
View at Amazon →
$610
View at Amazon →

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.

WDS400T2R0A

No Backblaze failure data for this model.

WDS400T4X0E

No Backblaze failure data for this model.