Shingled Magnetic Recording (SMR). This was a hard drive technology I was really excited for because of the increased storage density, and for photo use, high density at low cost is one of the most important things you can ask for. But, the crux of SMR hard disk drives, I realized as I started using my SMR hard drive for virtualization, is that SMR writes are slow. And yes, this actually makes them unsuitable for particular uses like RAID.
Therefore, there is a class-action lawsuit against Western Digital in the making due to not properly advertising and marketing its drives that were using SMR.
20200531/https://www.tomshardware.com/uk/news/wd-class-action-lawsuit-smr-hard-drive-us-canada