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Remote reset for Pogoplug E02 or GoFlex Net?

Posted by lorenzo 
Remote reset for Pogoplug E02 or GoFlex Net?
February 16, 2019 01:39AM
(First time poster so don't hesitate to point me to existing ressources/posts that I may have missed when searching)

Hi all,

I'm planning to leave powered-on a PogoPlug E02 or a GoFlex Net (most likely the GoFlex net) in a second home.

In case something happens, I'll have a second machine (currently HP microserver, running VmWare ESX, with remote management card), that I could wake/power-on remotely, and then connect to the E02 or GoFlex, using the serial console.

My problem is how to 'reset' the board: I installed uBoot + Debian (on E02 but will look into GoFlex Net soon) and everything works well, however if the Linux kernel hangs for any reason, I don't know if I can remotely reset the board.

Currently, I'm power-cycling it by commanding a relay from the HP microserver, but wondering if something simpler could be achieved.

Therefore:
1. is it possible to reset through the serial connection?
2. is there some kind of hardware watch dog mechanism on the board (so that if kernel hangs, the watch dog will detect this and reset automatically the board) ?
3. would the JTAG/OpenOCD approach allow reset (I think so but never used JTAG yet) ?

All advices are welcome, thanks for your help!
Re: Remote reset for Pogoplug E02 or GoFlex Net?
February 16, 2019 01:26PM
lorenzo,

> Currently, I'm power-cycling it by commanding a
> relay from the HP microserver, but wondering if
> something simpler could be achieved.

With PogoPlug E02 or GoFlex Net, once it was powered down or hung, you can not reset the box with serial console or JTAG. And it does not have hardware watchdog.

With serial console, you can reboot the box, whether it stops in u-boot because the rootf is corrupted, or stop in kernel booting process (i.e. ramdisk) because it cannot mount the rootfs.

So your solution is already the best, the only setup that can take care of all scenarios remotely: be able to power-cycle the box using a hardware gadget that you can control from another working box. And do a soft reset when it got stuck in the booting process.

-bodhi
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Re: Remote reset for Pogoplug E02 or GoFlex Net?
February 17, 2019 12:51PM
Thanks a lot Bodhi for your answer (and all of the hard work!).

It seems like, at least for the PogoPlug E02, there's a hardware watchdog, according to:

Dockstar watchdog supported?

At the time of the post, using this watchdog timer may have been a bit tricky (like using a specific user app, which I could not download anymore, but it may be in the internet archive machine), however with a recent kernel, checking dmesg, I can indeed see an entry:
23.648320] orion_wdt: Initial timeout 21 sec

and initial testing seems to confirm that the /dev/watchdog behaves like it should (and the kernel module would also suggest this is really the hardware watchdog).

Also I was not 100% clear on my goals:
1. use a 24/7 low-power server like Pogo E02 or GoFlex Net
2. use hardware watchdog to reset in case of kernel hanging
3. also implement an app to send some 'alive' packets (so I know it's still working and responsive)
4. be able, in case of problems (i..e not receiving the alive packets, and the hardware watchdog reset is not enough to fix it), to troubleshoot the box from a normal server that would powered just in this case.

I think the combination of hardware watchdog + a relay (which is, when not energised, giving power to the Pogo or GoFlex, but can be turned off by the normal server) is the simplest solution to achieve the above.

Will let you know how it goes (partial status: Pogo E02 is fully functional, GoFlex Net is semi-bricked :-), i.e. just uboot access but I have backup of the mtds, and a second one to play with, will post in another thread) , many thanks again.
Re: Remote reset for Pogoplug E02 or GoFlex Net?
February 18, 2019 03:31AM
Lorenzo,

If you already have a relay, watchdog is realy not necessary, IMO.

Besides, you could get orion_wdt working in Debian, but that does not take care of the scenario when uboot hang :) so you still have to detect the system hang up even the with watchdog anyway. Not too much additional benefit on top of the relay.

-bodhi
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Re: Remote reset for Pogoplug E02 or GoFlex Net?
February 18, 2019 07:36AM
Agreed, the watchdog is not really necessary, however it could make things easier in the case where a (successful) reboot fixes the problem (sounds more like a Windows problem-solving method rather than Unix method though).

If for any reason uBoot hangs, kernel doesn't start properly, or rootfs is corrupted, then serial access (for kwboot or console access) and ability to reboot are the only way to remotely try to fix the issue.

-lorenzo
Re: Remote reset for Pogoplug E02 or GoFlex Net?
February 18, 2019 01:52PM
lorenzo.

> If for any reason uBoot hangs,

In this case, the relay is absolutely needed. Otherwise, the power cord must unplugged/replugged.

-bodhi
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