WD Red Hard Disks: CMR vs SMR

Replacing a single 6TB CMR Red drive with an SMR (before WD's sneaky substitution became common knowledge) in a 6-drive RAID5 more than tripled the time it took my ReadyNAS to perform a scrub and totally locked up everything else while it was happening.  Had I not gone to SSH and canceled the scrub, allowed other stacked up processes to complete, and then resumed the scrub, it may never have completed.

Replacing that drive with an 8TB (still CMR) Red eliminated the problem, confirming it was the SMR drive that caused the issue.

My conclusion is that SMR drives have no business in any RAID system and WD should be taken to court for selling those pieces of junk as acceptable for that use.

Hi Stephen

Thank you for your quick reply, especially as It's been such a long time since I've been here.

As it happens, I was watching a YouTube video about the differences between SMR and CMR Red drives and how WD are trying to sneakily sell them to customers without making them aware of the pit falls.

For myself, I'm worried about compatibility issues, e.g. will these SMR drives work with my current CMR ones or even work with my old ReadyNAS's OS (probably not). 

TBH, my problem is that I have recently bought an unused ReadyNAS Duo v2 on eBay, the original user bought but never actually used it, he decided to go with Synology instead.  Since I have a couple of RNDuo v2's already, and I'm familiar with this device, I jumped at the chance to get another one. And once I can verify it is in good working condition, I intend to populate it with WD Reds.

But I now see that WD Reds are not just the Reds I bought a few years ago, an unfavourable variant has now been introduced that should be avoided at all cost.

Finally, does anyone know why WD is trying to introduce SMR drives in such a sneaky way and so trash it's reputation that it has built up over the years?

UK Bob

PS. Is it true that there's a consumer class action against WD for the way they introduced SMR into the HD market?