SSDs don’t click, grind or whir — which is great, except that it robs you of the audible warnings a hard drive gives. To know how an SSD is holding up, you have to look at its numbers instead. The good news: those numbers are easy to read, and they tell you clearly how much life a drive has left and whether it’s heading for trouble.
SSDs wear out by writing. Their health is measured in life-remaining percentage and total bytes written — check those, not for noises, because a failing SSD stays silent.
An SSD doesn’t wear mechanically — it wears by writing. Each flash memory cell can only be written a finite number of times before it degrades, so the controller spreads writes evenly (wear-levelling) to make the drive last. Health, then, is largely about how much writing the drive has done relative to what it’s rated for.
That’s why the checks are different from a hard drive’s: there are no noises to listen for and no spinning parts to tire. The whole picture lives in the drive’s wear figures.
Read them with CrystalDiskInfo, a Mac SMART tool, or better still the manufacturer’s own utility (Samsung Magician, Crucial Storage Executive, WD Dashboard, Kingston SSD Manager and the like). The ones to watch:
The headline number — an estimate of wear. 0% used is fresh; approaching 100% means the drive is near the end of its rated life.
How much data has ever been written, compared to the drive’s rated endurance. Well within rating is healthy.
The reserve of spare blocks left to replace worn ones. A falling spare, especially near its threshold, is a warning.
Blocks that have failed and been retired. A rising count signals the flash is degrading.
Generic tools like CrystalDiskInfo read most SSDs and give a quick health verdict and wear percentage. But the manufacturer’s utility is usually the best source, because it understands that specific drive’s attributes properly and often adds firmware updates and health alerts. It’s worth installing the one for your brand.
On a Mac, where third-party SSDs are less common, tools like DriveDx surface the same wear data. Whatever you use, the aim is the same: find the life-remaining figure and the write total.
Because SSDs fail quietly, the warning signs are behavioural rather than audible. A drive that suddenly drops to read-only — you can open files but not save — is protecting worn-out flash, and it’s a clear signal to get your data off. Watch also for the drive disappearing or reconnecting intermittently, unexplained slowdowns or freezes, or files that won’t open.
Unlike a hard drive’s gradual decline, SSD failure — especially a controller fault — can be abrupt. If you see any of these, back up straight away rather than waiting.
Don’t defragment an SSD. Defragmentation was designed for hard drives, to gather scattered file pieces so the heads travel less — but an SSD has no heads and no penalty for scattered data, so defragging achieves nothing useful and simply burns through write cycles, shortening the drive’s life. Windows already knows this and leaves SSDs alone; don’t override it.
Do keep some free space and keep firmware updated — both help an SSD manage wear and stay healthy for longer.
Put simply: low percentage used, write total well within rating, full spare — the drive is healthy. High wear, a shrinking spare, or reallocated blocks climbing — the drive is ageing; make sure your backups are current and plan a replacement. Read-only mode, dropouts, or a “Caution” status — back up immediately.
Most SSDs comfortably outlast their rated writes in normal use, so a healthy check is the usual result — but because failure can be sudden, a current backup is still the only real safety net.
What people ask us most about checking SSD health.
Read its wear data with CrystalDiskInfo or, better, your drive maker’s own utility (Samsung Magician, Crucial Storage Executive, WD Dashboard and so on). Look at the life-remaining or percentage-used figure, the total bytes written against the drive’s rating, and the available spare. Since SSDs fail silently, these numbers — not noises — are how you judge health.
Watch its behaviour rather than listening for it. The clearest sign is the drive dropping to read-only mode — you can open files but not save — which protects worn flash. Intermittent disconnects, sudden slowdowns, files that won’t open, or high wear figures are also warnings. SSD failure can be abrupt, so if you see these, back up immediately.
No — never defragment an SSD. Defragmentation only helps hard drives by reducing head movement; an SSD has no moving parts, so it gains nothing and simply wastes write cycles, shortening the drive’s life. Windows automatically skips SSDs for this reason. To keep an SSD healthy, leave some free space and keep its firmware updated instead.
A read-only or high-wear SSD is telling you to get your data off. If it’s dropped out entirely, don’t keep power-cycling — send it in for a free diagnostic. Post it in from anywhere in the UK, or drop it to us in Belfast.