Ubuntu – USB 3.0 hard drives don’t spin down when “safely removed” from Nautilus

Depending on the partition format, and the partition number (both of which can be found with sudo fdisk -l), the syntax for the mount command would be something like this:
sudo mount -t ntfs /dev/sdb1 /media/mountPoint
Note that the command listed assumes three things:

1. That the partition is on sdb, and has the number of 1 (which is how you end up with /dev/sdb1)
2. That your partition is of the type ntfs (which most large capacity drives are, unless they're formatted for Macs (in which case they have hfs+ or similar as the formatting)
3. That you're trying to mount the drive to the location /media/mountPoint.

Each of those 3 items I just mentioned can be adjusted as is needed based on the type of partition being used, the location you want to mount the drive to, and the partition number of the drive.

EDIT
I just realized I forgot a crucial step. Assuming you are going to use the above mentioned command, you need to create the mount point first. So using my above example of using a mount point of /media/mountPoint, you will need to do this command before you attempt to mount the drive:
mkdir /media/mountPoint
If this command requires you to have superuser, prepend the mkdir command with sudo, which will allow the command to be run as superuser.

Valid for this Ubuntu at least:

$ lsb_release -d  
Description:    Ubuntu 14.04.1 LTS

---

I have found that:

$ udisksctl mount --block-device /dev/$device

... will mount /dev/xxx in the same style as automount,
that is - in /media/$USER/Disk_Label-or-UUID/ with the last level dir auto-created.

$ udisksctl unmount --block-device /dev/$device;  

... will umount the above, but not '-eject' memory card/USB reader content.

$ gvfs-mount --eject "file:///media/$USER/DISK_LABEL"  

... lastly appears to be equal to 'Safely remove' or 'Eject' - and that WITHOUT an immediate re-mount.

Note: $ udisksctl power-off --block-device /dev/$device;
... would otherwise be a 'natural' option, but is hampered by an immediate re-mount.

---

EDIT --- you could use this script to "umount all" without having to dig out the names:

#! /bin/bash
#
for device in $(mount | grep "/media/$USER/" | cut -d" " -f1); do
        echo Unmounting $device 
        udisksctl unmount --block-device $device
done

if you prefer eject, change the -f1 into -f3 in the cut command and the line with udiskctl with

gvfs-mount --eject "file://$device"

(I think --- you can have problem with correctly quoting labels with blanks in it; and you'll have warnings if the device has multiple partitions mounted).

---

$ lsblk

... will display all the available block devices (except ram disks, no sudo required).
RAM and loop --> lsblk --all .

---

How do I "automount" a labelled disk?

Bring up the Dash (hit the 'Super' key) and type 'startup appl' and 'Startup Applications' should appear, click on it. Click Add and type anything you want in 'Name' and 'Comment' fields. Then fill in 'Command' with your version of:

/bin/bash -c '/bin/sleep 5 && /usr/bin/udisksctl mount -b /dev/disk/by-label/GreenWD_3TB'

... where /dev/disk/by-label/GreenWD_3TB is anything suitable you find from
the display of ls -lR /dev/disk/* | less

---

More:
How to access gvfs mounts from command line?
How to mount drive in /media/userName/ like nautilus does using udisks