I guess proper redundancy is having different brands of equipment also in some cases.
Having a RAID5 crash and burn because the backup disk failed during the reconstruction phase after a primary disk failed is a common story.
https://web.archive.org/web/20220330032426/https://ops.faith...
It's not always easy, but if you can, you want manufacturer diversity, batch diversity, maybe firmware version diversity[1], and power on time diversity. That adds a lot of variables if you need to track down issues though.
[1] you don't want to have versions with known issues that affect you, but it's helpful to have different versions to diagnose unknown issues.
https://www.neoseeker.com/news/18098-64gb-crucial-m4s-crashi...