My old HFS-formatted external drive stopped mounting on my Mac after an unexpected disconnect. Disk Utility sees it, but I can’t access my files. I need help with safe Mac HFS data recovery options before I try anything that could overwrite or damage the drive.
If the drive has stuff you actually care about, the first move is simple: stop messing with it. HFS/HFS+ recovery can work in a lot of cases, including deleted files, emptied Trash, accidental formatting, or a drive that went weird after a macOS update. But the more you try random repairs, the more you risk making the recovery worse.
I’d handle it in this order:
- Stop writing anything to the drive. Deleted data can still be there, but new files may overwrite it.
- Check whether the drive itself is failing. For an HDD, check the SMART status using something like Disk Drill or DriveDx. Lots of bad sectors or serious warnings means you should treat the drive as unreliable.
- If it looks unstable but you can still read it, image the drive first. Work from the disk image instead of repeatedly scanning the original hardware.
- If the drive looks healthy and mounts or shows up normally, go straight to recovery software. Don’t run First Aid, don’t format it again, and don’t use repair tools before you pull off the files you need.
For HFS recovery, I’d start with Disk Drill. It supports HFS/HFS+, works with internal and external Mac drives, and the workflow is pretty straightforward even if you haven’t done data recovery before.
- Open Disk Drill and pick the HFS/HFS+ drive.
- Choose Search for Lost Data. For external drives, Universal Scan is usually the safer default.
- Let the scan finish.
- Preview the results before recovering anything.
- Save the recovered files to a different drive, not the problem drive.
If that doesn’t find the files, it depends on what actually happened. TestDisk can be useful when the whole HFS partition is missing, but it’s not very friendly if you’re used to normal Mac apps since it runs in a text interface. And if you have a current Time Machine backup, use that first. That’s usually the cleanest option.
Quick formats and emptied Trash situations are often recoverable because the file contents usually aren’t wiped right away. The problem starts when macOS or another app writes new data over the old space. That’s why speed matters, but careful speed, not clicking every repair button you can find.
I’d stop with DIY attempts if the drive doesn’t show up in Disk Utility, randomly disconnects, clicks or grinds, or recovery tools keep failing with read errors. Those are signs the issue may be physical. At that point, powering it on over and over can make things worse, and a proper recovery lab is probably the better call.
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Try a different cable, USB port, or enclosure before you assume the HFS volume itself is trashed. If macOS pops up “initialize” or “erase,” cancel it every time, then scan from a recovery app like Disk Drill only after the drive is showing consistently.
Expect the recovery to be boring, slow, and not guaranteed to come back with perfect folder names. An HFS/HFS+ drive that was yanked during a write can have a damaged catalog or journal, and that is the difference between “the files are mostly there but the volume won’t mount” and “the recovery app can only find loose file types with ugly names.”
I agree with the “don’t run First Aid yet” advice. Disk Utility First Aid is not a preview tool. It tries to repair the file system, and repairs mean writes. Sometimes that works, but if your priority is getting files back, you want a copy of the data before anything starts “fixing” the directory structure.
A small caveat on SMART checks: with external USB drives, SMART is hit or miss. Some enclosures pass it through, some don’t, and some make it look less useful than it is. So if SMART says “not supported,” that does not prove the disk is fine. Pay attention to behavior too: slow detection, disappearing from Disk Utility, freezing Finder, clicking, repeated disconnects, or scans that crawl at the same percentage are all bad signs.
If it were mine, I’d separate the problem into two cases:
If the drive stays visible and does not make weird noises, make an image or scan it read-only, then recover to another disk. Disk Drill is fine for that kind of user-friendly scan, especially if you want previews before paying attention to a big pile of results. The main catch is that you should not save recovered files back to the same external drive. That sounds obvious, but people still do it.
If the drive keeps dropping off the bus, don’t keep launching different apps at it all night. That is when DIY recovery can turn a recoverable drive into a worse one. A flaky drive should be cloned with something made for bad reads, or sent out if the files are valuable enough. Normal recovery apps are not great at dealing with hardware that is actively failing because they keep asking the same sick disk to behave like a normal disk.
Another thing people forget with old Mac-formatted drives is encryption. If it was encrypted with FileVault or formatted as an encrypted Mac OS Extended volume, the recovery path changes. You’ll need the password, and some tools may show nonsense until the encrypted layer is handled correctly. Same idea if it was part of a Time Machine disk, since the file layout can be annoying even when recovery technically works.
If you want a quick sanity check before buying anything, open Terminal and run diskutil list. Don’t erase, don’t initialize, just identify whether macOS sees the physical disk and whether it sees the HFS partition. Seeing the physical disk but not a mountable volume usually points more toward file system damage. Seeing the disk appear and disappear points more toward hardware, cable, bridge board, or power.
There’s a similar real-world discussion here if you want to compare symptoms before doing anything risky: HFS external drive recovery case.
The short version: don’t try to make the old drive usable again first. Treat it like a source you are extracting from. Recover to a different drive, judge tools by whether they can preview your actual files, and stop if the hardware starts acting unstable.
A drive that shows the right capacity is a very different job from one that shows 0 bytes, 4 KB, or some nonsense size. If the size is correct, a read-only scan with Disk Drill is reasonable; if the size is wrong, I’d stop blaming HFS and suspect the enclosure/USB bridge or the drive electronics first. Swapping the enclosure before scanning can save a lot of wasted time.