Shit happens, and hard drives fail. I woke up this morning to a "corrupted directory" notice and beeping noises coming from the server area under my stage. As a reminder, my main server holds an 8-disk RAID 5 configuration + a system drive, and has been running smoothly for quite awhile now. I'm in the process of rebuilding the array using the original drive (it is still spinning and accepts a rebuild option), but I've also ordered a replacement drive so I can shove the thing in if the RAID fails again. The rebuild will take 30 hours, so I have some time to wait for the replacement to arrive. :) The next time I build a RAID, I'm going to have a dedicated spare in the mix so I don't have to stress out about sourcing a matching drive.
The failure orphaned hundreds of files, which were recovered and placed in a useless directory structure by CHKDSK. Chris Emura has always warned me about data loss in RAID 5 failure and luckily, I am always backed up (onto a ReadyNas 600 system). When the RAID finishes its rebuild, I'll do a restore from the backups.
I'm on track for my failure rate of 1-2 drives a year (out of the 20 or so that I use).