The symptoms arrive in a fairly consistent order and none of them announce themselves as a disk problem. By the time anyone connects the two, the drive has often been deteriorating for weeks.
Mechanical symptoms get worse with every minute of running. Performance and logical symptoms give you room to act. Putting a symptom in the right category is effectively the whole decision.
It slows down. Files take longer to open, the machine hangs briefly on save, boot creeps up. The drive is retrying bad sectors repeatedly before eventually succeeding. Weeks of warning.
The noise changes. A new whine, an occasional tick, a start-up sound that was not there before. Not yet the click of death, but the same components beginning to struggle.
Files misbehave. Documents that will not open, photographs with corrupt blocks, folders appearing empty. The file system is intact; the sectors beneath it are not.
SMART reports errors. Reallocated sectors, pending sectors, uncorrectable errors. Any of these climbing means the drive is failing whatever else it claims about its health.
It disappears intermittently. Vanishing from the machine and returning after a reboot. Frequently the last stage before it stops returning at all.
Read the SMART data. CrystalDiskInfo on Windows and DriveDx on a Mac both do it without installing anything permanent. Reallocated sector count, pending sectors and uncorrectable errors are the three fields that matter.
Then check whether it still mounts. If it does, copy your most important files off immediately — now, before reading further. A failing drive that still reads is a gift and it will not last.
Then stop using it. Not after finishing what you are doing. Every hour a degrading drive stays in service spends readable sectors you may want back.
Unknowable, and that is honest. Could be months, could be tomorrow. What is certain is it will not improve. Copy everything off today.
No. It writes to the disk it is checking, and on a drive with failing sectors that write frequently cannot complete. It is the most common way a recoverable drive becomes a partial one.
Sustained slowness with no other cause is often a drive retrying bad sectors. Each retry succeeds eventually, which is why you see delay rather than failure. It is an early warning.
If it still mounts and you have a spare disk, a sector-level clone using a tool that skips errors rather than retrying them is reasonable. Avoid anything that hammers bad sectors.
Yes. New mechanical sound means components moving in ways they should not. Switch it off rather than finishing what you were doing.
The price does not change — from £300 +VAT. What changes is how much comes back, and that is not something money fixes.