>>The IT department decided they were done with their pets, moved everything to a big vSphere cluster, and backed it by a giant RAID-5 array. There was a disk failure, but that’s ok, RAID-5 can handle that.

Precisely why, when I was charged with setting up a 100 TB array for a law firm client at previous job, I went for RAID-6, even though it came with a tremendous write speed hit. It was mostly archived data that needed retention for a long period of time, so it wasn't bad for daily usage, and read speeds were great. Had the budget been greater, RAID 10 would've been my choice. (requisite reminder: RAID is not backup)

Not related, but they were hit with a million dollar ransomware attack (as in: the hacker group requested a million dollar payment), so that write speed limitation was not the bottleneck considering internet speed when restoring. Ahhh.... what a shitshow, the FBI got involved, and never worked for them again. I did warn them though: zero updates (disabled) and also disabled firewall on the host data server (windows) was a recipe for disaster. Within 3 days they got hit, and the boss had the temerity to imply I had something to do with it. Glad I'm not there anymore, but what a screwy opsec situation I thankfully no longer have to support.