Unable to detach (spindown) external USB HDD in 15.04; "Safely Remove" just remounts it

Question

I have an external USB 3.0 HDD with several partitions on it, and I can't safely remove it (spin it down) before unplugging in Ubuntu 15.04.

I can run "Unmount" on each partition; but after unmounting all partitions disk is still spinning (it vibrates and I hear the spinning), and I think it may be unsafe to unplug it in such condition.

There is a Safely Remove Drive context menu option in Nautilus, Safely remove parent device in left Unity panel, and there is the command udisks --detach /dev/sdb (recommended in this Ubuntu Forums post). After any of these actions HDD spins down for 0.4-0.5 seconds, and then it is detected again as plugged in; all its partitions are auto-mounted just like when I insert its USB cable for the first time.

In dmesg I see

[ 46.592192] usb 3-1: USB disconnect, device number 4
[ 47.003378] usb 3-1: new SuperSpeed USB device number 5 using xhci_hcd
...
[ 48.638436] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: (null)

Click "Safely Remove Drive" for second time:

[ 68.815860] usb 3-1: USB disconnect, device number 6
[ 69.229567] usb 3-1: new SuperSpeed USB device number 7 using xhci_hcd
....
[ 71.199942] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: (null)

How can I safely unmount and spindown an external HDD without having it get redetected in seconds?

Answer 1

First of all, you must unmount all partitions mounted on the USB HDD, then try detach it. I gave an example below with udisksctl

1 Use lsblk to see your USB HDD and all mounted partition on it:

Shell@localhost:~$ lsblk
sda      8:0    0 931.5G  0 disk 
├─sda1   8:1    0   128M  0 part 
└─sda2   8:2    0 931.4G  0 part /
sdb      8:16   0 501.8G  0 disk 
└─sdb1   8:20   0 500.2G  0 part /USBDRIVE

2 Unmount all mounted partition for USB HDD

sudo umount /dev/sdb1

3 Power off the USB HDD using next command :

udisksctl power-off -b /dev/sdb

replace /dev/sdb with the correct USB HDD.