Sorry, it wasn’t apparent and it really ate my lunch when WD quietly switched a bunch of their Red, allegedly “NAS” drives from CMR to SMR without informing customers and then acting all surprised once the customer base got really riled up as resilvers went from 1 hour to 17 or failed altogether.
WD continue this charade to this day, so only red plus and red pro HDD drives might be safe for TrueNAS data pool use. With WD, I’d verify by SKU that the drive is CMR/PMR as the packaging or general sales information is forevermore suspect. I’ve lost all trust in the company even as I continue to use their drives because the alternatives are not better.
The “Red” HDD “NAS” drives in question are device managed SMR, or DMSMR drives. They pretend to be CMR drives but only have a small CMR cache that then gets flushed into SMR sectors on occasion - but without telling the OS, which then freaks out because the whole pool is held hostage while the flush completes. Some SSDs do the same thing with fast flash up front flushing into slower flash in the back. All that might work in light use but craters under heavy workloads.
Even more galling is one of their HGST-subsidiary employees admitting at a ZFS conference that DMSMR drives are incompatible with ZFS - five years before WD decided to screw over their customers by shipping a drive that is marginally cheaper to make at the same price point, with the same packing, etc as CMR drives that are actually compatible.
As you can probably tell, I’m still pretty mad about all this.