I have a 2TB 3.5" hard disk attached to a powered SATA to USB 3.0 adapter, which is connected to my Raspberry Pi 2. The Pi will boot with the drive attached and the drive will show up in fdisk -l, but it takes ~20 seconds to do so. However, I cannot mount the drive at all. It is in EXT4 format and the main partition is at /dev/sda2 but if I do sudo mount -t ext4 /dev/sda2 /mnt/hdd the Pi hangs until it eventually fails to mount it, after around 5 minutes.

Is this a power issue? And if so, would a powered USB hub fix the problem?

  • 1
    If the SATA-USB3 adapter is adequately powered, it should be fine. Have you checked the /dev/sda2 partition for damage? Do you see any errors in the system logs relating to the drive? You can add nofail to the mount options in /etc/fstab if your RPi is hanging waiting for the drive on boot.
    – bobstro
    Sep 7, 2017 at 15:14
  • Things to try: a) Connect the drive to another Linux system and see if it mounts; it is possible that the drive is damaged or corrupted. b) Try another USB port on the Pi; it is possible that there is an issue with your port. c) Some USB 3.0 devices don't work well with certain USB 2.0 controllers. This would be uncorrectible on your Pi, without trying a different SATA to USB adapter. Oct 8, 2017 at 13:52

3 Answers 3


Same problem with my RetroPie so I used $ dmesg to see what happened as linux attempted to mount the USB drive. About half way through was a line in red that said -

usb 1-1-port2: Cannot enable. Maybe the USB cable is bad?

followed by -

usb 1-1-port2: unable to enumerate USB device

when I changed the USB cable all was fixed.

Love it when diagnostics point directly to the solution!


The Raspberry Pi 3 USB ports are USB 2.0 but will work with a USB 3 drive. The 20 second wait might be normal as part of the boot process. The drive itself probably does not begin spinning until it receives a command to wake it up.

It is good that the drive is self-powered. Also good that it is EXT4 format. The size you mention is not a problem.

On my Rpi3 my external drives automatically show up under /mount/ I do not need to manually mount them.

You can certainly set up symlinks using the ln command to make the whole drive, or particular subdirectories, show up anywhere else in the file system you like.

  • I think you have misunderstood my question. The RPi will detect the drive as being connected and show a valid 1.8T EXT4 partition, but any attempt to mount said partition will fail after ~5 minutes. Oct 1, 2016 at 17:32
  • What is the error when it fails? What does the system log say?
    – bls
    Apr 22, 2019 at 21:43

I have a powered usb 3.0 HD 2 tera ntfs. It mounts fine with or without the powered usb. I have no USB adapter, they are compatible with usb2 just slowed down.I think it may be a power issue. Does you HD have it's own power source? If not I, suspect this is the problem. Also try loosing the adapter it should work without it. It's hardware may not be supported.

  • Just to clarify I plugged the blue USB 3.0 cord directly into pi and also can use powered usb 2.0 hub. If it's a power issue usually you will see a lightning bolt upper right of screen upon boot for a second.
    – user52264
    Jun 7, 2018 at 21:15

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