External Drive Not Showing Up on Mac? 7 Things to Check

The drive worked last week. You plug it in, the Finder window opens, and there is no drive in it. Nothing on the desktop, nothing in the sidebar. Most people buy a disk repair utility at this point, before they know which fault they are looking at.

The Mac may not see any hardware at all. It may see the hardware and fail to mount the volume. Or it may mount the volume and still hide it from Finder. Three faults. The fix for each one has nothing to do with the other two, and the whole list below is arranged so you can stop as soon as you know which of the three you have.

Start by deciding which failure you have

Open Disk Utility, which lives in Applications, Utilities, or comes up with Spotlight. In its menu bar choose View, then Show All Devices. The default view hides the physical disks and lists only volumes, which is the wrong level for this job.

If the drive appears there, hardware is being detected and the problem is software: an unmounted volume, a filesystem macOS won't mount, or a Finder display setting. If nothing appears, no amount of filesystem work will help, because the Mac isn't talking to the device at all. That points at a cable, a port, the power or the enclosure, and a dead disk is one of its possibilities.

1. Check the two Finder settings that hide drives

Finder keeps separate switches for the desktop and the sidebar. Finder, Settings, General has a checkbox for External disks, and the Sidebar tab has its own. A drive that is mounted but unchecked in both places looks exactly like a drive that isn't there.

Terminal settles it in one line. Run ls /Volumes and look at the list. Every mounted volume has a folder in there, including the internal disk. If your drive's name shows up, it is mounted and the problem is presentation. If it doesn't, move on to the next check.

2. Ask the Mac what it can see

The command diskutil list prints every attached device, mounted or not, with its partition table and volumes. This is the single most useful piece of output in the whole process, because it separates "connected" from "mounted" in plain text.

Read it in two places. A whole disk near the bottom of the list with no mount point under its volumes is connected and unmounted. An APFS container showing "Not mounted" is the same story one level down. Then run diskutil info /dev/disk4, using the identifier from the first command, to get the name, capacity, filesystem, mount point and SMART status of that device.

If it is unmounted, mount it: diskutil mountDisk /dev/disk4, or select the volume in Disk Utility and press Mount. When a mount fails with an error, note the exact wording. "No such file or directory" and "Resource busy" point at two different faults, and the second usually clears after a restart.

3. Rule out the cable, the port and the power

This is the check people skip because it means standing up. Do it anyway, in the cheapest order.

Plug the drive directly into the Mac instead of through a hub, a dock or a monitor. A 2.5-inch portable draws its power from the port, and an unpowered hub that was fine for a keyboard may not be fine for a spinning disk.
Try a different cable. Charge-only USB cables exist, they fit, and they carry no data. If the drive came with a short cable and you swapped in a longer one from a drawer, the drawer is the suspect.
Watch the copy speed when it does mount. A drive that has dropped to USB 2 speeds is telling you the cable or port negotiated down, and large transfers will crawl for reasons unrelated to the disk's health.
Try a different computer. A drive that mounts elsewhere isn't dead, and the rest of this list then applies to the Mac instead of the hardware.
If you have a spare enclosure or a SATA-to-USB adapter, move the bare disk into it. That test tells you whether the enclosure's controller failed or the drive did, and it costs ten minutes.

4. Run First Aid on the disk, then the container, then the volume

With Show All Devices on, select the physical disk at the top level and run First Aid. Work down afterwards: the container next, the volume last. Repairing a volume while its container has a fault tends to fail in a way that reads like the volume itself is broken.

If First Aid can't unmount the volume, unmount it yourself first with sudo diskutil unmountDisk force /dev/disk4, then run First Aid again. First Aid is also honest about what it can do. It repairs the filesystem's bookkeeping, not the platter. A failure with an error code tells you something specific, so write the code down before deciding the volume is gone. And running it a third time on a drive that is already struggling gives the hardware more work to do, not a better result.

5. Check whether the filesystem is the reason

macOS reads four common formats and writes to three of them. That asymmetry explains a large share of "the drive is broken" reports, which turn out to be a disk the Mac mounted read-only on purpose.

APFS and Mac OS Extended: full read and write on a Mac, and Windows needs help or third-party software.
exFAT: read and write on both, no permissions, no journal. The usual choice for a disk that travels.
NTFS: read-only on a Mac out of the box. Editing is not a setting you can switch on.
FAT32: read and write on both, with a 4 GB limit on any single file.

A related case is the volume that Windows left in a dirty state. Windows "Shut down" is not a full shutdown by default, since Fast Startup hibernates the kernel, and the disk can keep a flag saying it was not closed cleanly. macOS sees a volume it can't trust and mounts it read-only, or refuses to mount it. The repair belongs on the Windows machine: start it, choose Restart rather than Shut down, then run chkdsk X: /f on that drive letter. This is the same class of problem described in the guide to moving files between a Mac and a Windows PC, and the format table there is worth reading before you buy the next disk.

6. The drive mounts, but nothing can find your files

Spotlight indexes external drives by default, and it stops indexing any volume you add to System Settings, Spotlight, Search Privacy. A disk parked in that list stays invisible to search forever while Finder lists it perfectly, which produces the strange report that the files are there but the Mac can't find them.

Two commands tell you where you stand. mdutil -s /Volumes/YourDrive reports whether indexing is on for that volume, and if it says indexing is disabled, sudo mdutil -i on /Volumes/YourDrive turns it back on. A volume formatted or restored on another machine can also carry a stale index folder, and deleting the hidden .Spotlight-V100 directory at the volume's root forces a clean rebuild. Expect that rebuild to take a while on a large disk, and note that the steps are the same ones in the guide to rebuilding a broken Spotlight index.

Some places are never indexed no matter what you do, and a network share is one of them. Apps that search by reading the folder directly don't care. FileSearch handles exactly this case: point it at an unindexed drive or share and it reads that folder, then says in its status line that it did so, so an empty result means the file isn't there instead of meaning nobody looked.

7. When the drive is fine and the Mac is the problem

A restart clears more USB faults than any other single action, because it rebuilds the state the driver stack keeps in memory. Safe mode goes a step further by loading a minimal set of extensions, and on an Intel Mac an SMC reset covers the power delivery cases a restart doesn't reach.

Sleep deserves its own line. Drives that vanish after the lid closes, or that produce the "Disk Not Ejected Properly" warning while nobody was touching the machine, are usually being put to sleep and woken in the wrong order. In System Settings, Battery or Energy Saver, uncheck "Put hard disks to sleep when possible", and eject the disk before you close the lid on a laptop that will spend the afternoon in a bag.

One more cause sounds like superstition and isn't. USB 3 traffic interferes with 2.4 GHz wireless, a problem Intel documented years ago and never fully went away. If your Wi-Fi or Bluetooth mouse drops every time the drive is plugged in, move it to a port on the other side of the machine, use a shielded cable, or accept that the two radios would rather not sit together.

Where the native apps help

None of these repairs a drive. They cover the four jobs that come up around one: measuring it, finding what is on it, proving a copy is complete, and knowing when to stop.

DiskBrew sizes a whole external drive as rings instead of a list, so the folder holding a hundred gigabytes shows up as the biggest slice rather than a number eleven levels down. It measures folders across every CPU core at once, and a folder it is not allowed to read is labelled as such, never counted as empty, which matters on a disk with permissions copied from another machine. It installs on macOS and Windows.

DiskSpeed answers the cable question with a number instead of a feeling. It benchmarks sequential read and write in megabytes per second plus random 4K operations per second, auto-detects internal and external drives, and keeps a history, so a run before and after a cable swap shows whether the port negotiated down. The test file is deleted when the run ends.

FileSearch reads an unindexed drive directly and searches it by name in a sortable table, with wildcards for when you know the shape of what you want. FileSteep searches inside files, not just by name, and its folder comparison is the honest way to check a rescue copy: point it at the original and the copy, and it lists what is missing on each side.

The order to work in

Look for the drive in Disk Utility with Show All Devices. If it isn't there, stop and test cable, port and power.
Run ls /Volumes and diskutil list. That tells you whether the volume is mounted, and gives you the identifier everything after this needs.
Mount it, then open Finder settings and check both External disks boxes.
Run First Aid on disk, container, volume, once each.
Check the filesystem, and if the disk came from a Windows machine, close it down properly there before trying again.
If it mounts and search can't find anything, check the Spotlight privacy list.
Restart before you buy anything.

If the drive is failing

Clicking, ticking, repeated disconnects in the middle of a copy and a SMART status that reads Failing are different from everything above. That is where the job changes, from repairing a disk to rescuing data. Copy what matters to another disk first, in small batches, starting with what you can't replace instead of what takes the most space. Reformatting a failing drive ends the argument about why it stopped mounting. It also ends the data.

One habit is worth more than any tool here: a backup that runs on its own makes a dead external disk an inconvenience instead of a loss. The drives that hurt are the ones holding the only copy.

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