Currently I 'm using my RPi 2 with a 1 TB external Toshiba USB drive.Back in the day, I had to set max_usb_current=1 in my /boot/config.txt file, because when I plugged it in it would keep trying to power on and end up turning off constantly.I'm using a 2.1A mobile phone charger.

Right now I'm running out of space in the disk, so I'm going to replace it with a 640 GB Toshiba disk I extracted from my old laptop, using a standard USB 3.0 2.5'' drive enclosure (id is 152d:0567), but I want to be able to use them together until the old one runs completely out of space.This enclosure has a switch for turning the disk on/off.If I power on the Pi with both drives plugged or plug first the 1 TB one and then switch the button of the other one, the moment it starts the other one is turned off for a moment, and then on again.This causes it to be remounted on the same location without having been umounted properly first, which leads to trouble later.If I do it the other way, plugging first the 640 GB one and then the other, both keep trying to turn on constantly to no avail, making "ticking" sounds of sorts.

I have both drives in my fstab like this:

UUID=748EFC2E8EFBE690 /media/sida1 ntfs-3g auto,users,rw,uid=pi,gid=pi 0 0
UUID=3EB2B30EB2B2C9A3 /media/pomf288 ntfs-3g auto,users,rw,uid=pi,gid=pi 0 0

And with manual udev rules for mounting when they are plugged in after boot:

KERNEL=="sd?1", ACTION=="add", SUBSYSTEM=="block", ATTRS{serial}=="20130716042605", RUN="/bin/mount /media/sida1"
KERNEL=="sd?1", ACTION=="add", SUBSYSTEM=="block", ATTRS{idProduct}=="0567", ATTRS{idVendor}=="152d", ATTRS{manufacturer}=="JMicron", ATTRS{product}=="USB to ATA/ATAPI bridge", RUN="/bin/mount /media/pomf288"

What sort of problem can this be? A friend of mine who also has a Pi 2 has two 3.5 drives attached to it without a problem.

  • 1
    I'm not sure what you are asking. Do both drives work properly when they are properly powered? If so you are not giving them enough power.
    – joan
    Feb 3, 2016 at 20:48
  • Yes, they do.The problem is that turning one of them on while the other is plugged will cause it to be remounted without having been umounted first, causing it to be mounted multiple times on the same location. Feb 3, 2016 at 20:53
  • 1
    Use a powered USB hub to power the drives Feb 3, 2016 at 20:57
  • That USB Id tracks to a JMS567 chipset (I guess the OEMs don't bother to apply their own Id number) as used in something like this Tooploo 2.5" 3.5" SATA HDD Docking Station Enclosure USB 3.0 Interface EU {don't know how long that link will last!} Doesn't the enclosure have it's own wall-wart Mains PSU unit? Are you sure that your custom udev rules are not being overridden by the "built-in" ones?
    – SlySven
    May 4, 2016 at 0:15

1 Answer 1


It sounds like a power issue. Your RPi might be giving them enough power once the drives are started, but remember, the initial start is what requires the biggest power draw. If you're going to run both drives at the same time, they should be connected through an externally powered USB hub.

  • 1
    Same result with an externally powered USB 3.0 hub: one drive turns on and the other one keeps going on and off forever. Feb 3, 2016 at 21:11
  • What's the power supply to the hub? I'd also suggest trying usb Y cables to maximise the current available to each drive.
    – goobering
    Feb 4, 2016 at 12:11

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