I was responsible for maintaining some large glusterfs clusters built on top of these drives, and they certainly added excitement to the experience.

1) At one point we were experiencing disk failures often enough that we wrote a cronjob to detect drive failures via smartctl and automatically send an email to our hosting company requesting them replace the drive. This saved engineering time, and more importantly reduced time to drive replacement, because

2) On at least one occasion, we had the third drive in a RAID6 array fail before we had rebuilt from the initial failure, leading to loss of the array. We think the increased load of the rebuild increased the chance of subsequent failures. Needless to say recovering from this destroyed all plans (and sleep) for the weekend it happened.