reboot without log

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reboot without log

Postby lestofante » Tue Jul 21, 2015 9:45 pm

Hi,

recently i started monitoring my raspberry uptime, and found out it reboot many times ever day. There is no log on journalctl, and even the command "last reboot" show a very long list of "still running".

I don't have ANY physical access to the rapsi, only ssh, so its harder to debug.

Any idea? it use an external USB hub with 2A@5v (so 10w) and an external HDD.

Also tried to get an idea of what was going on, but seems everything fine, CPU at 12%, ram 117/178, swap 8/511... seems like it easier when syncthing is running, maybe because it use the external HDD? maybe some power issue? it is 40°celsius there, so maybe heat? why i get no log?
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Re: reboot without log

Postby WarheadsSE » Tue Jul 21, 2015 10:39 pm

Are you powering the Pi from the hub?

40C is sustainable, since the CPU is made to withstand twice that.

You could check the configuration for journald to see if the storage is set to persist or not.
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Re: reboot without log

Postby lestofante » Wed Jul 22, 2015 7:06 am

Yes, it.is powered from USB and i have log from precent boot, ad persistent is enabled. But there is no entry on reboot.

Edit: to clarify, rpi B is connected to hub by power connect or and by one USB. Usb HDD is connected to hub.
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Re: reboot without log

Postby WarheadsSE » Wed Jul 22, 2015 1:33 pm

You should _not_ be powering the device from a USB hub.
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Re: reboot without log

Postby lestofante » Sat Jul 25, 2015 10:20 pm

why i should not?

the USB hub has 2A rating, and the power line are in parallel between all USB ports, so is not a probelm of power negotiation.

Now i tried disabling Synchthing, less reboot but still there.

Finally decided to remove the external disk from fstab (to be sure there is no usage at all) an i got no reboot in more than 10 hour.
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Re: reboot without log

Postby WarheadsSE » Sun Jul 26, 2015 5:58 pm

Because the specifications for USB 2.0 call for an allowance of only 500mA per port, and anything outside of that is not reliably identical or appropriate. If all the power is parallel you are going to see power browning when sudden draws occur. Instant CPU death.
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Re: reboot without log

Postby sdjf » Sun Jul 26, 2015 6:23 pm

There are some USB hubs that have a specific connector meant to power devices that can deliver more power, and I am not at all clear if lestofante is using one of those, or a standard USB port. If it is a port meant to power devices, it still may not deliver enough power.

Multiple reboots like you are experiencing are a clear sign of inadequate power supply or a bad power cable or connector, as far as I know.
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Re: reboot without log

Postby lestofante » Wed Jul 29, 2015 8:52 am

Yes the hub is an active hub, and until march I never had problem.
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Re: reboot without log

Postby WarheadsSE » Wed Jul 29, 2015 2:33 pm

I am hard-line on this issue. Test with a real, dedicated, appropriately sized power supply for the Pi.
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Re: reboot without log

Postby lestofante » Wed Jul 29, 2015 5:30 pm

Unmounted and removed the disk from fstab, I had no random reboot again. Maybe is because temp is 40°c and the supply goes in protection? Anywhay the raspi is in another country, so no way to physically access for at least a couple of month, or even more xD
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