SMART Report Explainer (is my hard drive or SSD failing?)
Paste your drive's health report and get a straight answer: fine, keep an eye on it, back up today, or stop using it.
The drive's own overall check still says PASSED or Good. That headline only flips when a reading crosses the maker's limit, which is often very late, so trust the individual numbers below.
What the readings say
Every reading, explained
| ID | Reading | Raw value | What it means |
|---|
How it works
Paste the full text from smartctl -a (or -x), CrystalDiskInfo (Edit, Copy) or PowerShell's Get-PhysicalDisk | Get-StorageReliabilityCounter | Format-List. It is read in your browser; nothing is uploaded. Serial numbers aren't shown in the results, so the summary is safe to share when asking for help.
The explainer reads the attribute table (smartctl decimal IDs or CrystalDiskInfo hex IDs with hex raw values), the NVMe health page, and the overall PASSED/FAILED line, works out whether it's a hard drive, SATA SSD or NVMe SSD, and judges the readings that actually predict trouble: pending, uncorrectable and reallocated sectors, spin retries, CRC errors (usually the cable), temperature, age, SSD wear, Available Spare, media errors and NVMe critical warnings.
The verdict is the worst single finding: Looks healthy, Keep an eye on it, Back up today, or Stop using it. It also says whether the problem is the drive, the cable, heat or just age. When the drive's own headline still says PASSED or Good but a reading says otherwise, you get a warning, because that headline only flips at the maker's limit, which is often too late.
The rules are common rules of thumb rounded for clarity, not a guarantee: drives can fail with a perfect chart, so keep backups either way. Vendor-packed counters (like Seagate's huge read error rate) are listed but not judged. Background: how to get the report on each system, reallocated vs pending sectors, SSD health percentage and the Wirebook drive check-up lesson.
Questions
How do I get a SMART report?
Windows: CrystalDiskInfo, then Edit, Copy. Mac: brew install smartmontools, then smartctl -a disk0. Linux: sudo smartctl -a /dev/sda (or /dev/nvme0). USB drives often need -d sat.
My drive says PASSED. Why does this say back up?
PASSED only means no reading has crossed the maker's failure limit. Pending or uncorrectable sectors mean some data already can't be read, long before that limit.
Are CRC errors a sign my drive is dying?
Usually not. They count data garbled on the cable or USB adapter. Reseat or replace the cable and check that the number stops growing.
What does Percentage Used mean on an NVMe SSD?
How much of the maker's rated write endurance is used. It can pass 100% and the drive usually keeps working, but plan a replacement.
Is my report uploaded?
No. Everything is parsed in your browser. Nothing is sent, stored or logged.