Is your Mac's SSD about to die? How to find out

Your data can be lost in the blink of an eye. Here's how to get a heads up before it happens.
Written by Adrian Kingsley-Hughes, Senior Contributing Editor

What data do you have on your Mac right now? Of that, what isn't backed up?

What would you do if it was gone?

SSDs (Solid State Drives) are much more reliable than HDDs (Hard Disk Drives), but that doesn't make them invulnerable. The downsides of SSDs compared to HDDs is that you get little to no warning when they are starting to malfunction, and when they die, it's generally permanent.

So, in addition to having a backup or two (you should always have at least two backups of your important data), it's a good idea to keep an eye on your Mac's storage drive.

But how do you do that?

One key metric of SSD wear is measured in TBW, or TeraBytes Written. It's a feel-good number that storage manufacturers come up with to measure storage life (think MTTB or Mean Time Before Failure for hard drives).

Typically, a 250GB SSD will have a rating of 60 and 150TBW, which means that even at the lowest end of the rating to exceed this number in a year, you'd have to be writing more than 100GB of data onto that 250GB drive EVERY DAY.

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A tool I use for keeping an eye on my storage drive is DriveDX. In addition to how much data has been written to the disk, this gives access to more than a dozen other parameters.



The four that I like to keep an eye on are:

  • Life Percentage Used
  • Data Units Written
  • Media and Data Integrity Errors
  • Critical Composite Temperature Time

If everything is green, you're OK. Keep up with your backups and you should be in good shape. 

If everything isn't green, you need to drop everything and get your drive replaced as soon as possible.

These are the ones I find worth keeping an eye on. Life Percentage Used and Data Units Written will increase over time as the drive is used, but Media and Data Integrity Errors and Critical Composite Temperature Time problems are signs of immediate problems.

Critical Composite Temperature Time also highlights how keeping the SSD cool can help prolong its life. As already mentioned, SSDs are much more reliable than HDDs, but the one thing that I find dramatically shortens their lifespan is overheating.

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