Sadly, it’s not a question of if but when your Mac’s hard drive or SSD will stop working, and essentially it doesn’t matter which operating system you are using. In fact, it’s easy to fall into the trap of believing the myth that different HDD lifespans are related to specific operating systems, but the reality is that the length of a drive’s life depends on many factors, starting with the brand through to the capacity and interface used. As for the average lifespan of an HDD in a Mac, there is no clear consensus but it’s a pretty safe bet to assume that it will last on average somewhere between four and five years. That is, of course, under ideal conditions.
Standards expressing a hard drive’s lifespan
From Seagate’s perspective, MTBF is archaic and it no longer uses this statistical term related to data integrity. Originally developed for the military, MTBF is expressed in power-on hours (p.oh.) and is often a specification associated with hard drive mechanisms. WD puts the MTBF of its drives at over a million.
Since it considers MTBF “not representative”, Seagate has moved to a new standard, AFR. This is similar to MTBF and differs only in the way it measures units: AFR is the probable percentage of failures per year based on the manufacturer’s total number of installed units of a similar type, whereas MTBF measures the probable average number of service hours between failures.
Real-life tests
You may not have a controlled environment where it is possible to test hard drives of different capacities from various manufacturers, but cloud backup firm Backblaze does. The hard drive failure rate was 1.84% for the third quarter of 2017, but the annualized number reached 2.07%, as explained by Backblaze in a blog post. Although that doesn’t sound like much, it still means that of the 86,529 drives Backblaze has access to, 1,791 are going to fail!
To put that into perspective, just think about the differences between your Mac and their data center. All their drives are kept in optimal conditions while your Mac is exposed to all sorts of varying factors that you might not even think about, such as variations in voltage and current fluctuations or sudden spikes (like during a storm). Then there is the portability of a MacBook, which adds further physical ‘stress’ on the hard drive.
How long will my Mac’s hard drive last?
This depends on multiple different factors, but keep in mind just one key detail: one fifth of Backblaze’s optimally stored HDDs stopped working in the third year of their life. That puts the average lifespan of a hard drive at around four years, though you can safely hope for longer if your Mac isn’t powered on 24 hours a day, seven days a week. The newer storage type, the solid-state drive, is estimated to last much longer – around 50 years – but that’s still just theory as this new technology hasn’t been around for that long.
Fortunately, hard drives include a handy monitoring tool called S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology), which Mac optimization apps such as CleanMyMac make use of to display HDD health warnings, if applicable. They will warn you if the disk is about to fail, so it can be replaced before it stops working forever and your data is lost.
Replace hard drive or switch to SSD?
It is possible to save some money by doing the upgrade yourself by buying the storage disk from a reliable retailer such as MacSales, and putting your nervous system and your technical skills to the test by taking the Mac apart and installing the new drive yourself. Note that this life-saving ‘surgery’ is not as easy as a RAM upgrade, however.
The safest options are to either visit an Apple Authorized Service or an Apple Store and let a specialist replace the failing storage disk for you. But this way you’ll need to shell out much more, because there will be an added service cost on top of the hardware expenses.
István F.
Adam B.
