Western Digital and Toshiba encode their drives differently from Seagate and from each other, and in both cases the code carries more useful information than Seagate's does. WD's suffix letters map closely onto product line and generation, and Toshiba's mechanism prefix separates conventional from shingled almost cleanly.
Have the part number in front of you? Paste it into the resolver and get the verified answer with the manufacturer document it came from.
A WD drive number is WD, then the capacity, then a suffix of four letters. WD40EZAX is WD, 40 for 4TB, then EZAX. Capacities below 10TB use two digits for terabytes; at 10TB and above the pattern shifts to three digits, so WD101EFBX is 10TB and WD181KFGX is 18TB.
The suffix is where the product line lives, and unlike Seagate's generation digits it is reasonably readable once you know the families.
The middle letters generally identify the line and the last letter tends to move with generation. That is a useful heuristic rather than a rule, and it breaks often enough that you should verify rather than assume.
| Suffix | Line | Built for | Example |
|---|---|---|---|
| EZEX / EZBX | WD Blue | Desktop, conventional recording | WD10EZEX |
| EZAZ / EZRZ / EZAX | WD Blue | Desktop, varies by capacity | WD20EZAZ |
| EFAX | WD Red (old) | The 2020 shingled NAS models | WD40EFAX |
| EFZX / EFPX / EFRX | WD Red Plus | NAS, conventional | WD40EFZX |
| KFGX / KFBX / FFBX | WD Red Pro | NAS, 7200rpm, 5yr | WD181KFGX |
| PURZ / PURX | WD Purple | Surveillance | WD43PURZ |
| PURP | WD Purple Pro | Surveillance with analytics | WD241PURP |
| FZEX / FZBX | WD Black | Performance desktop | WD4005FZBX |
| SPZX / SPSX | WD Blue / Black 2.5in | Laptops | WD10SPZX |
Every model number here resolves to a page with the WD document that establishes its recording technology.
EFAX is the suffix worth recognising on sight. Those are the WD Red models at 2TB, 3TB, 4TB and 6TB that shipped with shingled recording into a NAS-marketed line without it being stated, which produced the 2020 controversy and the litigation that followed.
WD's response was to publish a model-level list of which client drives are shingled, and to split the Red line: Red Plus with the EFZX, EFPX and EFRX suffixes is the conventionally-recorded NAS line, and Red Pro above it. If you are buying a WD NAS drive today, Plus or Pro is what you want and plain Red is a name to be careful with.
The other pair to know is within WD Blue at the same capacity. WD20EZBX is conventional and WD20EZAZ is shingled, one letter apart, same family, same 2TB, opposite answers. That is the WD equivalent of Seagate's 1TB BarraCuda problem.
Toshiba numbers its bare mechanisms and its retail cartons differently, and the mechanism number is the informative one.
DT01ACA is the conventionally-recorded 7200rpm desktop mechanism, covering 1TB, 2TB and 3TB. DT02ABA is the shingled 5400rpm mechanism, covering 2TB, 4TB and 6TB. That split is close to a clean rule: DT01 is conventional, DT02 is shingled, and Toshiba's own product overview for the DT02 series states drive-managed shingled recording explicitly.
The retail P300 cartons map onto those mechanisms. HDWD110, HDWD120 and HDWD130 are the 1TB, 2TB and 3TB conventional drives. HDWD240 and HDWD260 are the 4TB and 6TB shingled ones, and Toshiba names both in its April 2020 SMR statement.
So a P300 can be conventional at 7200rpm or shingled at 5400rpm depending only on the capacity you picked, under one product name. It is the same trap as the others, expressed differently.
| Prefix | Line | Recording | Example |
|---|---|---|---|
| DT01ACA | Desktop mechanism, 7200rpm | CMR | DT01ACA100 |
| DT02ABA | Desktop mechanism, 5400rpm | SMR | DT02ABA400 |
| HDWD1xx | P300 retail, 1-3TB | CMR | HDWD130 |
| HDWD2xx | P300 retail, 4-6TB | SMR | HDWD240 |
| HDWG | N300 NAS | CMR | HDWG440 |
| HDWR | X300 performance | CMR | HDWR440 |
| HDWL | L200 laptop 2.5in | SMR | HDWL120 |
| MQ04 | 2.5in mechanism | SMR | MQ04ABF100 |
| MG | Enterprise capacity | CMR | MG09ACA18TE |
The WD suffixes and the Toshiba prefixes are more informative than Seagate's generation digits, and they are still not a substitute for looking the model up.
WD changes suffix letters across generations, so a pattern that holds today may not hold for a drive released next year. Toshiba's DT01 and DT02 split is clean now and is a mechanism naming convention rather than a promise about future products.
The reliable move is the same for all three manufacturers: read the part number off the label, look it up against the maker's own document, and treat anything unverified as unverified rather than as probably fine.
Our resolver does that lookup and names the document. If a model is missing, search it anyway, misses decide what gets verified next.
It is a WD Blue desktop suffix, and at 2TB and 6TB those are the shingled models on WD's own client SMR list. The EZBX and EZEX suffixes at the same capacities are the conventionally-recorded ones, so within WD Blue the suffix is what decides the answer.
Red Plus is the conventionally-recorded NAS line WD created after the 2020 episode in which the EFAX-suffixed Red drives shipped with shingled recording into a NAS-marketed line without disclosure. If you are buying a WD NAS drive today, Plus or Pro is what you want.
The DT02ABA desktop mechanisms are, per Toshiba's own DT02 series product overview which states drive-managed shingled recording. That covers the 2TB, 4TB and 6TB models and the retail P300 cartons built on them, HDWD240 and HDWD260.
HDWD110, HDWD120 and HDWD130 are the 1TB, 2TB and 3TB P300 cartons on the conventional DT01ACA mechanism. HDWD240 and HDWD260 are the 4TB and 6TB cartons on the shingled DT02ABA mechanism. Both the carton and the mechanism resolve to the same answer here.
As a guide to family and generation, yes. As a substitute for looking up the recording technology, no. Manufacturers change suffix conventions across generations, and within every one of these families there are capacities where the answer differs from its neighbours.