Apple’s macOS 11.4 Update Fixed SSD Wear Reporting on M1 Macs
In February, news broke indicating that some M1-based Macs were writing far more SSD data than they should have been. We dug into the numbers and found little evidence of a trend. While some people reported eye-popping figures of as much as 347GB of data per hour being written to their drives, it was always possible that this was a measurement error — not an actual data-writing error.
According to Hector Martin, one of the individuals who first reported the problem, the issue may have been resolved in macOS 11.4.
Update on the macOS SSD thrashing issue: It seems the issue is fixed in 11.4. Feel free to try the betas if you’re adventurous, or wait for the final release.
It’s going to be interesting diffing the XNU kernel source once it drops and seeing what the bug was…
— Hector Martin (@marcan42) May 23, 2021
AppleInsider reports that a source they spoke to at Apple confirmed that the problem was always an issue with what the OS was displaying, not what it was actually doing behind the scenes. If you’ve been spooked by concerns that you’re killing your laptop by using it, rest easy. You haven’t been.
AppleInsider also reports that macOS 11.4 now properly reports uptime statistics, whereas previously, it didn’t. Both the number of uptime hours and the total amount of data supposedly written to SSD seemed off in the initial reporting, so we’re glad to see evidence that these were minor bugs rather than evidence of a hardware issue.
SSD wear is one of those problems that everyone was quite concerned about when drives started shipping, but that has mostly failed to be an issue, ever, in shipping products. Long-term storage projects that robustly benchmarked drives for months at a time produced no evidence of significant failure issues. Recent reporting from Backblaze suggests that SSDs may be more reliable than hard drives, though they caution that these figures could change as their test SSDs age.
Despite this generally high degree of reliability, drive manufacturers continue to work to improve overall quality in various ways. Zoned Namespaces are an upcoming innovation to storage that allows for a substantial reduction in DRAM and overprovisioning. Western Digital estimates it can cut its provisioning by a factor of 10, and it won’t need to equip drives with ~1GB of RAM for every 1TB of drive capacity.
Zoned Namespaces won’t come to the consumer market for a few years yet, but we’re already seeing a few signs of life in the enterprise market. Samsung has a QLC SSD with ZNS support on the way. One of the other advantages of ZNS: By reducing write amplification, it allows even QLC drives to be enterprise-level products, though they’ll still never match the performance of a TLC or MLC drive.