Some (all?) rebranded "WD Ultrastar" drives still report themselves as "HGST" as their SMART device models. I'm not sure how does Blackblaze count them. Perhaps

Some (all?) rebranded "WD Ultrastar" drives still report themselves as "HGST" as their SMART device models. I'm not sure how does Blackblaze count them. Perhaps they're (correctly) counted via the SMART model regardless of branding? Update: This issue has been covered in the Blackblaze 2020 report. They apparently existed in parallel. The original HGST drives, while still existed as of 2020, were being gradually phased out... > These drives obviously share their lineage with the HGST drives, but they report their manufacturer as WDC versus HGST. The model numbers are similar with the first three characters changing from HUH to WUH and the last three characters changing from 604, for example, to 6L4. We don’t know the significance of that change, perhaps it is the factory location, a firmware version, or some other designation. If you know, let everyone know in the comments. As with all of the major drive manufacturers, the model number carries patterned information relating to each drive model and is not randomly generated, so the 6L4 string would appear to mean something useful.