I have a Raspberry Pi 3 to which I need to plug an external HD. Such HD is a WD My Passport, which is powered directly from USB and it works perfectly with my laptop. At the first connection attempt, the HD led didn't even stay on. Conscious of the power limitations of the Raspberry Pi 3, I maximized the USB current output by adding the line max_usb_current=1 to /boot/config.txt Now the HD's led stays on and is correctly recognized by the lsusb command as follows:
Bus 001 Device 004: ID 1058:25e2 Western Digital Technologies, Inc.
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. SMC9514 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
However, I cannot find the disk anywhere in the system. Indeed if I look at dmesg this is what I observe:
[ 260.551388] usb 1-1.3: new high-speed USB device number 4 using dwc_otg
[ 261.483575] usb 1-1.3: New USB device found, idVendor=1058, idProduct=25e2
[ 261.483586] usb 1-1.3: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 261.483595] usb 1-1.3: Product: My Passport 25E2
[ 261.483602] usb 1-1.3: Manufacturer: Western Digital
[ 261.483610] usb 1-1.3: SerialNumber: 575832314443364632304C36
[ 261.484621] usb-storage 1-1.3:1.0: USB Mass Storage device detected
[ 261.490655] scsi host0: usb-storage 1-1.3:1.0
[ 262.562475] scsi 0:0:0:0: Direct-Access WD My Passport 25E2 4004 PQ: 0 ANSI: 6
[ 262.565247] scsi 0:0:0:1: Enclosure WD SES Device 4004 PQ: 0 ANSI: 6
[ 262.565731] sd 0:0:0:0: [sda] Unit Not Ready
[ 262.565745] sd 0:0:0:0: [sda] Sense Key : 0x4 [current]
[ 262.565757] sd 0:0:0:0: [sda] ASC=0x44 <<vendor>>ASCQ=0x81
[ 262.584641] sd 0:0:0:0: Attached scsi generic sg0 type 0
[ 262.652202] scsi 0:0:0:1: Attached scsi generic sg1 type 13
[ 442.591949] sd 0:0:0:0: timing out command, waited 180s
If I touch the HD, I can feel it doesn't spin. Also, it occasionally beeps every random amount of minutes. Could this really be a power issue? As far as I know, enabling max_usb_current=1 should provide currents up to the USB3.0 standard. The HD is the only thing connected to the Raspberry Pi 3 and the power supply provides 2.1A.