Western Digital Sued to Permanently Block SMR in NAS HDDs

Western Digital continues to face fallout for its decision to ship shingled magnetic recording (SMR) HDDs in NAS products. The law firm suing the company has updated its filing to add significant technical data and is not requesting a huge payday for itself. Instead, the plaintiffs ask that Western Digital be forbidden from advertising SMR drives as being suitable for NAS applications.
If you haven’t been following the story, we’ll summarize it below:
Conventional hard drives use CMR (Conventional Magnetic Recording). They write data to magnetic tracks and read information off those tracks using a drive head. CMR drives lay each track down independently, with guard banding on either side. In SMR drives, the tracks are laid down in partly overlapping fashion.

Seage has also deployed shingled magnetic recording to boost the areal density of its drive platters, though the technology isn’t a great fit for consumer products.

This method of overlapping data allows for higher density per HDD platter, theoretically allowing for fewer platters and saving the drive manufacturer some money. The performance trade-offs, however, are significant, particularly in certain types of write workloads.
The problem with putting SMR drives in a NAS is that they’re terrible at it. While performance is acceptable (if slow) in some common use-cases, there are other real-world scenarios that SMR drives simply cannot handle.
SMR drives don’t perform writes the same way an HDD does — they actually go through a program/erase cycle more akin to an SSD, because “shingling” the tracks makes it impossible to write to just one track at a time. The drive head has to read the data off an entire block of the hard drive before writing the block back to disk with its now-modified contents. This requirement is why SMR drives are unsuited to certain kinds of work.
A month ago, end-users discovered WD was putting SMR drives in its WD Red product family. Red is specifically intended for NAS applications and Western Digital advertises the drive as suitable for consumer and commercial deployment. There’s a lawsuit against the company for this, based on the fact that CMR and SMR drives cannot be deployed in some RAID arrays side-by-side, and that WD is selling these drives into products that cannot use them properly.
The plaintiffs in the case are not alleging that the SMR drives are defective, but that Western Digital has engaged in false advertising by selling these products for uses they cannot materially fulfill. This is not in question: It’s been factually demonstrated that file systems like ZFS and certain types of RAID configurations are incompatible with SMR.
The plaintiffs and their lawyers are not seeking cash damages. What they want is a ruling declaring Western Digital cannot advertise SMR drives as being suitable for NAS systems when they very much are not. The updates to the original...