USB hard drive disconnects and reconnects spontaneously

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I've got a USB hard drive (Intenso 320GB 2.5") which is plugged into my Pi.  
It auto-mounts to /media/pi/<ID number> but I umount it from there and  
manually mount it to a folder /mnt/recordings where it is used as the  
destination for TV recordings made by TVheadend.

I've noticed that at random times (not related to movement of the USB  
connection between drive and the Pi), the drive disconnects itself. The  
first I know is when I see a pop-up dialogue "Removable media is inserted -  
Open in File Manager". It remounts to /media/pi/<ID> - always the same ID.  
However I notice that the raw device /dev/sda and sda1 changes to  
/dev/sdb(1) and then sdc(1), and so on for each successive disconnection and  
reconnection.

I was going to reconfigure TVheadend to refer to the /media/pi/<ID> mount  
point, but there's something that prevents TVHeadend working in this case,  
even though I can "ls" the files on the drive and the mount point has 777  
permissions.

Any suggestions? The drive is formatted as NTFS. Could that be relevant:  
does NTFS have some sort of auto-dismount capability.

I'm about to try another drive to see if that fails in the same way. I  
didn't notice a memory stick (formatted as exFAT) fail in this way, even  
though it appears as the same raw device /dev/sda(1).

The drive has been used for ages on various Windows PCs without any signs of  
auto-dismounting.  


Re: USB hard drive disconnects and reconnects spontaneously
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I think you have a loose connection or a faulty controller (on one side
or the other).

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The successive device names imply that this is about the device, nothing
to do the filesystem on it.

--  
https://www.greenend.org.uk/rjk/

Re: USB hard drive disconnects and reconnects spontaneously
On a sunny day (Wed, 19 Sep 2018 09:04:14 +0100) it happened "NY"

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Looks like a power failure to the drive to me,
could be caused by a bad USB connector or power supply not strong enough.
You can check that when if it changes from sdb1 to sdc1 by typing
 mount
to see when it says sdc1 if sdb1 is still mounted,
that would mean it is not properly un-mounted, check cable... power supply.

I have had a _lot_ of bad USB cable incidents all over the place.
USB drives take a lot of power, current on the USB.



Re: USB hard drive disconnects and reconnects spontaneously
NY wrote:

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You could link /mnt/recordings to /media/pi/<ID number>, or bind-mount it
on /mnt/recordings. This way it will be available there immediately once it
reconnects.


Re: USB hard drive disconnects and reconnects spontaneously
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It's happened with a different disk (Transcend) so it looks as if it's the  
Pi that's doing it. I wonder whether it's a power supply issue, as someone  
suggested.

I'll try linking /mnt/recordings to /media/pi/<ID number> - is it better to  
make a hard link or a symbolic one? I've not heard of bind-mounting. I'll  
research it.

I'll also get a powered USB hub. I've seen warnings about not powering too  
many things from the Pi itself, even if it has a Pi-branded 2.5A PSU. I  
hoped I'd be able to stay under the limit. I've read something about a  
low-voltage warning as a symbol in the top right of the screen, but I've  
never actually witnessed it.  


Re: USB hard drive disconnects and reconnects spontaneously
NY wrote:

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If it actually is a hardware issue, it is of course better to resolve that.

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I have never used hard links, all my linking works fine being soft :-)

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It is a way to mount an already mounted resource simultaneously at another
place, the manpage should suffice for explanation as it is easy to do.

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That might help, as stability depends on peak current consumption of the
drive.
OTOH I am running an SSD off the Pi without any problems, current uptime is
158 days.


Re: USB hard drive disconnects and reconnects spontaneously
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Sounds an excellent idea to be able to mount a device in two places in the  
filesystem.

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I've just checked the voltage at the +5V and GND pins on the GPIO and *at  
the time of testing* I'm getting 5.1V, so definitely not below spec. It is  
interesting that with the drive in a different USB port (bottom left rather  
than bottom left, looking with the Ethernet port to the left of the USBs)  
the new drive hasn't bombed out yet.

But I think a powered hub might be useful - or else a HDD with its own power  
supply. I have one somewhere - but I can't think where that "somewhere"  
might be :-)  


Re: USB hard drive disconnects and reconnects spontaneously
On 19/09/2018 12:27, NY wrote:
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It may well only be dropping when a certain pattern of activity is  
occurring - high CPU load, disc being accessed, other peripherals  
active, so you really need to check when stressing the system.

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I would always recommend running a spinning disc from a separate power  
supply. Small consumer spec SSDs are OK to power from the Pi.

---druck

Re: USB hard drive disconnects and reconnects spontaneously
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Yes it's my own fault. I've seen it recommended not to power "greedy"  
devices like spinning HDDs and even DVB-T adaptors from the Pi itself. I'll  
get a powered hub.

It's been running for a good many hours now with a pen drive in place of the  
spinning HDD, so it's not a generic USB port problem. I wonder where I put  
my HDD that has its own power supply - those are usually a PITA but this  
might be a case where it comes into its own ;-)  


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