SMART check on external USB hard disk on macOS

Question

I recently tried getting smart status for my WD My Passport USB hard drive. I first ran $ smartctl -a /dev/disk3 but clearly the output was bound to be:

smartctl 7.2 2020-12-30 r5155 [Darwin 18.7.0 x86_64] (local build)
Copyright (C) 2002-20, Bruce Allen, Christian Franke, www.smartmontools.org

Smartctl open device: /dev/disk3 failed: Operation not supported by device

I checked smartmontools wiki to find instructions about its usage with USB hard drives and found out you have to add -d with the correct driver, in my case it's -d sat. Unfortunately the output of the correct command on macOS Mojave is:

$ smartctl -d sat -a /dev/disk3     
smartctl 7.2 2020-12-30 r5155 [Darwin 18.7.0 x86_64] (local build)
Copyright (C) 2002-20, Bruce Allen, Christian Franke, www.smartmontools.org

/dev/disk3: Type 'sat+...': Not a device of type 'scsi'
=======> VALID ARGUMENTS ARE: ata, scsi[+TYPE], nvme[,NSID], sat[,auto][,N][+TYPE],usbcypress[,X], usbjmicron[,p][,x][,N], usbprolific, usbsunplus, sntjmicron[,NSID], sntrealtek, intelliprop,N[+TYPE], jmb39x[-q],N[,sLBA][,force][+TYPE], jms56x,N[,sLBA][,force][+TYPE], auto, test <=======

Use smartctl -h to get a usage summary

Am I doing something wrong? I noticed everyone else is getting the correct output with the same command.

Thanks in advance.

Answer 1

If you read down that list, see how many have been tested to work on macOS… I can't find any.
It's generally accepted that you can't get SMART data over USB on Macs, because they don't provide SCSI passthrough.

There are some exceptions requiring an extra plugin available from the makers of DriveDx, who note…

If you want to perform external drive diagnostics on OS X – currently there is only one option – you can install 3rd party kernel extension – SAT SMART Driver. SAT SMART Driver is free open source project (published under Apple Public Source License) by Jarkko Sonninen. It is hosted on GitHub.

If you want the driver, access it through the DriveDx page linked above, as they link to various versions for different purposes. Also linked are how-tos for specific OS versions.

smartmontools refers to this on their USB devices and smartmontools page…

The ​OS X SAT SMART Driver provides access to SMART data for SAT, JMicron and Sunplus capable USB and Firewire devices on Mac OS X. On OSX El Capitan (10.11+) you may need a signed driver, which can be downloaded from the ​DriveDx website. Note that this does not support 48-bit ATA commands (-l xerror) or non-SMART ATA commands (-s apm,N). Full USB support would require SCSI pass-through support which does not yet exist on Mac OS X.