Rapid blinking blue LED - why?

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Rapid blinking blue LED - why?

Postby CollieJim » Thu Nov 27, 2014 3:15 am

I have Arch Linux running on a Cubieboard2 with a 500GB SATA drive attached. The power supply claims to be 5v @ 2.6A. I use it for a simple nfs file server.

Normally I see a blue double-blink about once per second. Twice now in the morning the device has been unresponsive and the double-blinks are more than twice as fast. What does it mean, other than the generic "a problem has occurred"?

I cannot get in via ssh to see logfiles or otherwise see what is happening. I use a wired connection. I get either 'no route to host' or 'connection refused'. This occurrs whether the disk is attached or not.

Where do I look next?

Thanks
CollieJim
 
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Re: Rapid blinking blue LED - why?

Postby ap82 » Thu Dec 11, 2014 11:13 am

This happened to me before after doing an update and i just said yes to everything which over wrote the boot script. Did you do a update like that?
ap82
 
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Re: Rapid blinking blue LED - why?

Postby krabat » Thu Dec 11, 2014 11:55 am

The blue LED normally indicates the "heartbeat". Thus an increasing frequency indicates that some process is causing a higher system load.
LEDs can be handled both by U-Boot and Linux.
From within Linux the purpose of LEDs can be seen by commands like
$this->bbcode_second_pass_code('', '
# cat /sys/class/leds/cubietruck:<color>:usr/trigger
')The actual is in brackets, the available others aren't. Description of LED (e. g. "cubietruck:blue:usr") varying with kernel and device. See also StatusLEDs on linux-sunxi.org. Just fyi, though, as it has to be run from a shell and hence is not an option right now.

As the problem, what ever it is, seems to screw your network connection completely, there are only two options to further investigate that I'd know.
Mount the SD card's root partition on another Linux box featuring systemd, open the journal by 'journalclt --file=<path to *.journal on SD card> or chroot into the Arch Linux root partition and run journalctl as usual. The latter only works if the host used to mount the SD card is ARM too, afaik.
Plug a serial adapter and watch the boot procedure from a serial console.
krabat
 
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Re: Rapid blinking blue LED - why?

Postby CollieJim » Thu Dec 11, 2014 3:31 pm

Thanks for the replies.
So far it has only happened twice. There have been no problems for several days, and nfs is working.

I currently have another micro connected to the Cubie2 via ssh, and a USB-serial adapter connected to my desktop system. Now, since I am a bit more prepared, it probably won't happen again.

I've checked the journal and have found a number of times that /var/lib/rpcbind/rpcbind.xdr and portmap.xdr could not be opened, and other network related errors. Due to the system clock being reset each time power is applied I have no idea when they occurred. I'll examine the journal more to see what else I can find.

It looks like my next task is to set up ntp, or at least install a clock.
CollieJim
 
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Re: Rapid blinking blue LED - why?

Postby krabat » Sun Dec 14, 2014 6:41 pm

$this->bbcode_second_pass_quote('CollieJim', '
')another micro connected to the Cubie2 via ssh
=?! Another micro SD card? A faulty SD card could obviously be the reason for a complete failure much as RPC problems could make the network fail.

As for an NTP client you could give systemd-timesyncd a try which can be used with network tools other than systemd-networkd as well. It can by launchend by simply running
$this->bbcode_second_pass_code('', '
# systemctl enable systemd-timesyncd.service
')see man systemd-timesyncd.
It does make sense to completely delete the journal when doing so. At least in my experience journalctl once started showing crappy results when I started using an NTP client only after the system had been booted several times without adjusting the system time.
krabat
 
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