The WD WD Red 4TB (WD40EFAX) uses SMR recording.
Verified against: WD Red NAS HDD product brief ยท Checked
WD's own Red product brief prints SMR against this model, footnoted as device-managed SMR.
Shingled recording overlaps tracks like roof tiles to raise density. Reading is unaffected, and for sequential work, archives, media libraries, backup targets, files written once and read many times, this drive is genuinely fine and the saving is real. The problem is sustained random writing, because modifying data under an existing track can force the tracks above it to be rewritten too. A RAID rebuild or a ZFS resilver is hours of exactly that pattern with no idle time to recover, so a 4TB WD40EFAX in an array can extend a rebuild dramatically, and the rebuild window is precisely when the array has no redundancy left. Do not put this drive in a NAS or a parity array.
| Model number | WD40EFAX |
| Brand | WD |
| Family | WD Red |
| Capacity | 4TB |
| Form factor | 3.5" |
| Rotational speed | 5400 RPM |
| Cache | 256 MB |
| Recording technology | SMR |
| Workload rate | 180 TB/year |
| Warranty | 3 years |
| Status | Current |
| Replaced by | โ |
A dash means the manufacturer does not state that field for this exact model. We leave it blank rather than filling it from a retailer listing.
If this drive is going into an array, a NAS, or anything that rebuilds, shingled recording is the wrong choice at any price. These are conventionally-recorded drives at this capacity or one step up, in stock right now with live prices.
| Drive | Capacity | Recording | $/TB | Price | |
|---|---|---|---|---|---|
| 695842-001 4TB SAS 6G | 4TB | CMR | $15.00 | $60 | Buy |
| 012GYY 4TB SAS 6G Renewed | 4TB | CMR | $21.25 | $85 | Buy |
| DRMYH Compellent 4TB NL SAS Renewed | 4TB | CMR | $22.50 | $90 | Buy |
Verified CMR model numbers at this size: ST4000VX007, ST4000VX016, ST4000VN006, ST4000VN008.
It is SMR. That comes from WD Red NAS HDD product brief, which is WD's own documentation for this exact part number rather than a capacity-level summary or a retailer listing.
We would not. Shingled recording turns a rebuild into hours of the write pattern it handles worst, which can extend the window during which your array has no redundancy. For sequential and archival use outside an array this drive is fine.
A conventionally-recorded drive at 4TB or one step up. The table above lists what is in stock right now with live prices, and every model number linked there has its own verified page with the manufacturer source.