Almost every hard drive and SSD keeps a health log called SMART (Self-Monitoring, Analysis and Reporting Technology): counts of damaged sectors, read errors, temperature, hours of use and, on SSDs, how much of their rated life is used. On a Mac, the quickest check is Disk Utility: select the drive, click the Info button, and look for S.M.A.R.T. status. “Verified” means the drive reports no failure. “Failing” means copy your files off now.
Two catches. macOS only shows that one-word summary, not the numbers behind it. And many external drives don’t show any SMART status at all, because the USB enclosure doesn’t pass it to the Mac.
Check SMART status in Disk Utility
- Open Applications ▸ Utilities ▸ Disk Utility.
- Choose View ▸ Show All Devices, so you can see the physical drives and not just their volumes.
- Select the drive itself: the top line, not a volume indented under it.
- Click Info in the toolbar and find S.M.A.R.T. status.
If Disk Utility reports that the disk has a fatal hardware error, Apple’s advice is to back up as much as you can and have the disk replaced; no repair tool can fix it.
Other places macOS shows it
- System Information: open Applications ▸ Utilities ▸ System Information, then under Hardware choose NVMExpress (most Mac SSDs) or SATA. Each drive lists its S.M.A.R.T. status.
- Terminal: run
diskutil listto find the drive’s identifier, thendiskutil info disk0 | grep SMART(with your identifier). It answers Verified, Failing or Not Supported.
What the answers mean
| Status | What it means | What to do |
|---|---|---|
| Verified | The drive reports nothing failing | Keep a current backup; drives can still fail without warning |
| Failing | The drive itself says it’s failing | Copy what matters now, then replace it |
| Not Supported, or no line at all | The connection doesn’t pass health data | Unknown, not healthy. Watch for the warning signs below |
Why external drives often show nothing
macOS reads SMART from drives on Thunderbolt and USB4 connections, but most USB 3 enclosures and adapters don’t pass it through. So a portable hard drive or USB SSD will often show no status, or Not Supported, however healthy or unhealthy it is. Some enclosures do pass it; plugging the drive in directly, without a hub, gives it the best chance.
See the details with Reco’s Drive Check-up
Reco is a free Mac app, and its Drive Check-up reads what the drive reports about its own health and puts it in plain words.
- Open Reco and select the drive in the list.
- Choose Drive Check-up under More ways Reco can help or from the Tools menu.
- Read the verdict: Looks healthy, Worth watching (early signs of wear), Copy it now (the drive reports damage), or Can’t tell (no health data came through). Below it are the plain-language findings, such as how many damaged sectors have been replaced with spares, read errors the drive couldn’t correct, its temperature, hours powered on and, for SSDs, how much of its rated life is left. The raw numbers are listed too.
Drive Check-up only reads the drive’s health log; nothing is written to the drive. When a card, USB stick or enclosure passes no health data, Reco shows Can’t tell rather than guess. A drive that reports nothing wrong can still fail without warning, so a backup is never wasted.
Warning signs SMART may not catch
- Clicking, grinding or repeated spin-up sounds from a hard drive.
- The drive disconnects on its own, or Finder hangs when you open it.
- Copies fail or slow to a crawl partway through.
- Files that opened before now come back damaged.
A growing count of damaged or unreadable sectors is the clearest sign in the numbers. A few replaced sectors can stay stable for years; a count that keeps rising means the surface is wearing out.
If the drive is failing
- Copy the files that matter most first, to a different drive. Don’t run First Aid or reformat first; repairs write to a drive that may not survive many more hours.
- If ordinary copying fails, use Reco’s Copy first to make one careful copy of the whole drive to a disk image. You can stop and pick up where you left off. Then recover files from the copy, not the drive.
- If the drive clicks, doesn’t spin up, or doesn’t appear in Disk Utility, turn it off. No software can read it, and every power-on can make it worse. A data recovery lab is the next step.
Then replace the drive. To pass the old one on, wipe it first.
Questions
What does S.M.A.R.T. status “Verified” mean on a Mac?
That the drive isn’t reporting a failure right now. It’s a one-word summary, not a guarantee: drives can fail without warning, and some early signs of wear don’t change it. Keep a backup either way.
What should I do if Disk Utility says S.M.A.R.T. status is Failing?
Copy what matters to another drive straight away, before you try any repair. A failing drive can stop working at any time, and First Aid can’t fix hardware. Then replace the drive.
Why does my external drive say SMART is not supported?
Most USB enclosures don’t pass the drive’s health data to the Mac. Thunderbolt and USB4 drives usually do. Not supported says nothing about the drive’s health, good or bad.
How do I check my Mac SSD’s remaining life?
macOS only shows the overall status. Reco’s Drive Check-up reads the details an SSD reports, such as the share of its rated life used, spare space left and errors, and explains them in plain words.