Over the past week, some Mac M1 users have reported alarming readings of SSD health, suggesting that these devices are writing extraordinary amounts of data to their drives (via iMore).
On Twitter and the MacRumors forums, users report that M1 Macs experience extremely high disk writes in a short period of time. In what appear to be the most severe cases, Mac M1 would consume up to 10-13% of its SSD’s maximum guaranteed total bytes written (TBW).
Flash memory on solid state drives, such as those used on Macs, can only be written a certain number of times before it becomes unstable. The software ensures that the load is distributed evenly across the memory cells of the drive, but there comes a point when the drive has been written so many times that it can no longer reliably hold the data. So, while SSD wear and tear is normal, the expected behavior, drives should not exhaust their capacity to hold data as quickly as some M1 Macs appear to be.
One user showed that his Mac M1 had already consumed one percent of its SSD after just two months, while another Mac M1 with with a 2TB SSD had already consumed three percent. The total number of data units written to these machines is several terabytes, which would normally be expected to be considerably less.
The user with three percent utilization speculated that if her machine was a 256GB model, she could have used up to 30% by now and peaked at TBW in about two years. An SSD can continue to function once its TBW limit is reached, but it is not known how long it will last beyond that point.
It is not known how widespread the problem of TBW is, but reports Weird SSD behaviors are also now emerging from Intel-based Mac users, which suggests that the TBW issue may not be exclusive to M1 Macs.
The reported wear is so extreme on some M1 Macs that it suggests the issue is due to a bug rather than the expected behavior of the M1 chip, but it is not known whether the issue is with faulty reads or macOS actually writing. large amounts of data on the drive. Sometimes drive monitoring tools are unreliable, and the issue is likely to be fixable with a macOS Big Sur update.