Tuesday, April 12, 2022

Mac S.M.A.R.T. Support: USB-C vs. Thunderbolt

Howard Oakley:

Although macOS has supported storage connected via USB-A ports since 1998 and USB-C since 2015, it has never supported access to S.M.A.R.T. attributes on storage connected using those ports. FireWire support was rather better, and Thunderbolt should give S.M.A.R.T. access by default. This can be confirmed in Disk Utility, or in the Storage item in System Information, where the last entry for each supported physical drive gives its current S.M.A.R.T. status.

Apple’s simplistic entry for S.M.A.R.T. status doesn’t even report when this was last checked, but several excellent third-party utilities give more detailed access. My favourite substitute remains DriveDx, but there are others, and the free command tools in smartmontools which enable you to roll your own with modest effort.


However, for any third-party utility to be able to monitor storage connected by USB, the SAT SMART kernel extension has to be installed. Although this does apparently run on M1 series Macs as well as Intel models, macOS can’t run at Full Security on an M1 when it requires loading third-party kernel extensions.

Howard Oakley:

The simple answer might be to admit that M1 Macs don’t provide full support for USB-C storage, and that we should use Thunderbolt instead. The current premium for a 2 TB SSD is around $/€/£ 100, whether you buy a complete drive or assemble one yourself using an enclosure. But in many cases, that surcharge is largely wasted.

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