Hi,
I am doing tech support for a family member, but I am pretty unfamiliar with Macs.
He had noticed that Time Machine had not run in a while, so I opened it, and his former Time Machine drive could not be found. It wasn't showing up on the Desktop or in Finder, so I opened Disk Utility to see that it is unmounted. When I tried to mount it, it did nothing. I verified the LaCie drive and it returned no errors. I verified the disk, and it failed and returned "Underlying error: 8: POSIX reports: Exec format error". I tried to repair the disk and it returned the same thing.
I am not sure if it has been working since he upgraded to Mavericks.
It seems to me that the drive is dead, pre-reformat, but let me know if not. (I am not sure why it would have failed. He doesn't seem to turn off his computer, and I doubt he has unplugged the drive at any point. It may have been running for several years straight, though.) If it's dead, is the data likely recoverable? If so, could you point me to some good resources for this?