I dropped a 4TB mechanical external hard drive, and a few hours later my Mac could still detect the physical disk over USB, but the HFS+ volume would no longer mount. I had only partially backed it up to Backblaze, so I'm worried that more than 3TB of personal archives and multimedia may be gone.
Disk Utility identifies the volume as Mac OS Extended (Journaled), but First Aid fails with filesystem check exit code 8. Running diskutil verifyVolume reports that the journal needs to be replayed while the volume is read-only, along with "Invalid index key," "Invalid sibling link," and error -69845 indicating that filesystem verification or repair failed.
DiskWarrior initially managed to build a replacement directory, but it couldn't replace the original because of a Mac OS services failure. Its Preview function also failed with error codes 2160 and 2304. On another attempt, it reported: "Directory cannot be rebuilt due to disk hardware failure (-36, 2747)."
I have not erased, reformatted, or otherwise modified the drive. I want to preserve it and recover as much data as possible. Should I stop trying software repairs and have a professional assess the hardware first? If the disk is still readable, is making a sector-level image or clone with something like ddrescue a reasonable next step, and what are the realistic odds of recovering the files?
2 Answers
At this point, treat the drive as potentially failing hardware rather than just a damaged directory. A professional recovery service can inspect it and, if necessary, work with the platters or drive mechanism. Avoid repeated repair attempts, mounting it read-write, or running anything that could change the filesystem.
If the drive is stable and readable, the usual DIY priority is to make a sector-by-sector copy onto another drive at least as large as the original. ddrescue is commonly used because it can skip bad areas, record progress, and return to difficult sectors later. Ideally, preserve the original and perform filesystem repairs or file recovery only on the image or a duplicate. If the drive is making unusual noises, disconnect it and go straight to a recovery professional instead.
That makes sense. I’m trying not to do anything else to the original until I know whether it has a hardware problem.