A macOS command-line tool that reads SMART data and runs diagnostics on Western Digital external drives (MyBook, Elements, etc.) through the WD USB bridge enclosure.

WD external drives (MyBook, Elements, EasyStore) use a proprietary USB-SATA bridge that blocks standard SMART passthrough. Every existing tool fails on these enclosures:

• smartctl — returns "Operation not supported by device" on WD USB bridges
• OS-X-SAT-SMART-Driver (642★) — a macOS kernel extension (kext) for SAT passthrough. Last updated December 2016. Requires unsigned kext loading, which is impossible on Apple Silicon Macs (M1+). Its README explicitly states it is "not compatible to WD Drive Manager, or enclosures with custom kernel extensions."
• wdpassport-utils — Linux-only Python tool for WD Passport encryption/unlock. No SMART support.
• Seagate/openSeaChest (718★) — cross-platform drive utility. Cannot communicate through WD's proprietary USB bridge on macOS.
• wdepc — WD Extended Power Condition tool. Power management only, no SMART.

This tool takes a different approach: instead of trying to pass ATA commands through the bridge (which WD blocks), it talks to the bridge's SES (SCSI Enclosure Services) management interface using vendor-specific SCSI diagnostic pages — the same protocol WD Drive Utilities uses internally.

The result is a pure userspace CLI tool that:

• Works on Apple Silicon (no kext required)
• Requires no third-party dependencies
• Provides SMART data, self-tests, temperature, drive info, sleep timer, and erase
• Runs on any modern macOS version

None beyond Xcode Command Line Tools. Uses only macOS system frameworks (Foundation, IOKit, CoreFoundation). Does not require WD Drive Utilities.

xcode-select --install  # if not already installed

make

make test       # run 50 unit tests
make coverage   # run tests with llvm-cov coverage report

sudo ./wd_smart [command]

sudo ./wd_smart --disk 0 info   # first drive
sudo ./wd_smart --disk 1 info   # second drive
sudo ./wd_smart list            # show all connected WD drives

sudo ./wd_smart                # show SMART attributes
sudo ./wd_smart info           # drive identity and specs
sudo ./wd_smart short-test     # kick off a quick test
sudo ./wd_smart status         # check test progress/results
sudo ./wd_smart temp           # current drive temperature
sudo ./wd_smart sleep 30       # spin down after 30 min idle
sudo ./wd_smart sleep 0        # disable sleep timer
sudo ./wd_smart power-off      # safe eject / power off

# Encryption
sudo ./wd_smart set-password "mypassword"     # enable encryption
sudo ./wd_smart unlock "mypassword"           # unlock after power cycle
sudo ./wd_smart remove-password "mypassword"  # disable encryption
sudo ./wd_smart reset-dek --confirm           # nuke encryption key (DATA LOSS)

# Destructive
sudo ./wd_smart erase --confirm        # quick format (bridge-level)
sudo ./wd_smart secure-erase --confirm # full zero-fill (20+ hrs on 18TB)

sudo make install   # copies to /usr/local/bin

src/
  WDSmart.h          — Shared header (types, constants, declarations)
  WDScsi.m           — SCSI transport abstraction + command wrappers
  WDDevice.m         — IOKit device discovery and management
  WDCommands.m       — SMART parsing, info, temp, sleep, self-test, erase
  WDEncryption.m     — Password cooking and encryption commands
  main.m             — CLI entry point
wd_smart_tests.m    — 50 unit tests with mock WD drive emulator
Makefile            — Build, test, coverage, install
ARCHITECTURE.md     — Design decisions and testing strategy
AGENTS.md           — Protocol reference and development notes

• macOS (tested on Apple Silicon, arm64)
• WD MyBook, Elements, and other WD USB enclosures with SES interface
• Requires root (sudo) for IOKit SCSI exclusive access

MIT