In the last 25 years working with approximately 700 servers that used RAID 5 I saw two of them lose an entire volume. Once was due to a malfunctioning HP RAID controller, and the other was due to a second disk dying while the rebuild from the first failure was still ongoing. There turned out to be a systemic problem with that drive model’s firmware which almost certainly contributed.

So in my experience it’s rare but it definitely does happen.

It can get worse. About 20 years ago the company I was at had an EMC tech yank the wrong power supply from a Symmetrix rack, where the other supply had earlier in the day caught fire! We lost that entire rack’s data (customer’s personal email accounts) due to data corruption. It was probably around 300 10k SCSI disks in that rack, a multimillion dollar expense at the time, and we had to restore all of it from tape over many, many days. Really, really sucked.

Anything that came out when I was a kid is retro, so anything pre 1970s is retro. 80s or later is modern.