I currently deal with a few disk failures every week, all on RAID6 (on Dell H7xx controllers) and a few RAID-1 on HP and Adaptec controllers. Mostly SAS drives

I currently deal with a few disk failures every week, all on RAID6 (on Dell H7xx controllers) and a few RAID-1 on HP and Adaptec controllers. Mostly SAS drives, but a few older model SATA SSD drives (that are dropping like flies after lots of writes over a year). This is across about 32000 disks so the chances for some disk failure every week is high. The RAID controllers work as advertised almost always, file system intact. Sometimes there's a performance degradation during a disk rebuild, but only on arrays where disk i/o is near max ability. There has been, I think two, catastrophic failures, for example when there's an issue with the cable or backplane, causing corruption, then having more than two disks go corrupt before getting to the bottom of it and invalidating the entire array. That said we have very few issues with power, and the batteries have died on many of the controllers, so I'm not sure how it will pan out on dodgy data centre power flapping.