Yeah, hard disk. The server was used when we bought it, and to our knowledge the failed disk is original (it came with the server). That would make the disk 8 years old and well past the end of its useful life. If we had the money, I would suggest we fully re-disk the server since the others are just as old, but considering we lose money month after month, it's not in our interest to replace disks that still work, regardless of their age.