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#1 2018-12-02 15:41:44

UglyBob
Member
Registered: 2015-11-29
Posts: 43

Debugging server without monitor

I have a small server in the wardrobe and it has some issues with powering off and starting again as it should. It is not the first time and usually ends with me having to drag a monitor into the wardrobe for debugging. Pretty tired of that procedure.

So I wonder, is there any way to debug this kind of problems using for instance a usb cable from a laptop? Ssh is not an option as it loses connection when powering off begins and doesn't get network when it gets stuck in boot either. Any ideas?

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#2 2018-12-02 15:49:13

Slithery
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From: Norfolk, UK
Registered: 2013-12-01
Posts: 2,996

Re: Debugging server without monitor


No, it didn't "fix" anything. It just shifted the brokeness one space to the right. - jasonwryan
Closing -- for deletion; Banning -- for muppetry. - jasonwryan

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#3 2018-12-02 15:52:04

Trilby
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Registered: 2011-11-29
Posts: 20,437
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Re: Debugging server without monitor

https://wiki.archlinux.org/index.php/Wo … al_console

Last edited by Trilby (2018-12-02 15:52:14)


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#4 2018-12-03 07:46:34

UglyBob
Member
Registered: 2015-11-29
Posts: 43

Re: Debugging server without monitor

Slithery wrote:

Not really, it is a Brix (intel nuc). Could it be emulated over USB perhaps?

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#5 2018-12-03 16:10:26

ewaller
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From: Pasadena, CA
Registered: 2009-07-13
Posts: 16,274

Re: Debugging server without monitor

Something like this https://www.newegg.com/Product/Product. … gnorebbr=1 will provide a serial port over USB, but, you will have to configure the system to use it for the console


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
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#6 2018-12-03 18:58:12

UglyBob
Member
Registered: 2015-11-29
Posts: 43

Re: Debugging server without monitor

ewaller wrote:

Something like this https://www.newegg.com/Product/Product. … gnorebbr=1 will provide a serial port over USB, but, you will have to configure the system to use it for the console

But neither the server nor the laptop has a rs232 port, so should I then buy another converter and convert it back to usb? hmm

Is it not possible to do it directly over usb somehow with a male<->male cable?

https://www.datapro.net/products/usb-3- … cable.html

Last edited by UglyBob (2018-12-03 19:00:10)

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#7 2018-12-03 19:13:57

ewaller
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From: Pasadena, CA
Registered: 2009-07-13
Posts: 16,274

Re: Debugging server without monitor

UglyBob wrote:

Is it not possible to do it directly over usb somehow with a male<->male cable?

https://www.datapro.net/products/usb-3- … cable.html

No.   At least in no practical manner.  I would wager that the neither device is a client. And if they were, I would not have a clue as to how to configure things.


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

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#8 2018-12-04 11:30:31

sincomil
Member
Registered: 2018-02-13
Posts: 77

Re: Debugging server without monitor

@UglyBob, you can use some of KVM-over-IP devices to do what you want.

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#9 2018-12-04 14:13:33

UglyBob
Member
Registered: 2015-11-29
Posts: 43

Re: Debugging server without monitor

sincomil wrote:

@UglyBob, you can use some of KVM-over-IP devices to do what you want.

Ah ok, but that sounds like an expensive solution?

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#10 2018-12-05 08:45:42

UglyBob
Member
Registered: 2015-11-29
Posts: 43

Re: Debugging server without monitor

I soldered together two FTDI cables (usb<->rs232), only tested the cable, but seems to work. So I think it would work for my server too if I can just configure it to output the logs on a serial port, but I saw some guide for that. Will post the result later tonight smile

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#11 2018-12-05 09:52:34

Mr.Elendig
#archlinux@freenode channel op
From: The intertubes
Registered: 2004-11-07
Posts: 3,956

Re: Debugging server without monitor

As a sidenote: Some of the GB Brix models/versions have a serial port header even though they don't have an external connector.


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#12 2018-12-05 15:16:09

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 16,274

Re: Debugging server without monitor

UglyBob wrote:

I soldered together two FTDI cables (usb<->rs232), only tested the cable, but seems to work. So I think it would work for my server too if I can just configure it to output the logs on a serial port, but I saw some guide for that. Will post the result later tonight smile

You might find this https://wiki.archlinux.org/index.php/Wo … al_console to be more satisfying than just getting the logs.  That article will tell you haw you can log in through that link.

Rather than soldering, I would get two FTDI USB to serial cables and a Female-Female null modem.  https://www.walmart.com/ip/DB9-Female-t … lerId=1148

Or, a pair of these https://www.banggood.com/FT232RL-FTDI-U … rehouse=CN and a three wires from a bundle of these https://www.adafruit.com/product/266


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

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#13 2018-12-10 13:52:04

UglyBob
Member
Registered: 2015-11-29
Posts: 43

Re: Debugging server without monitor

The cable seem to work fine, I can login over it if I enabled it in systemd (systemctl start serial-getty@ttyUSB0.service). But at first I couldn't figure out which boot loader I use so I can enable logging over it at boot. Now I think I figured out that it is systemd-boot (see info below). But I can't find any information how to enable log over serial port then. Also if I let systemd handle it, I can't get the logs from shutting down the system as the services dies to early.

$ bootctl status
System:
     Firmware: UEFI 2.31 (American Megatrends 4.654)
  Secure Boot: disabled
   Setup Mode: setup

Current Loader:
      Product: systemd-boot 227
          ESP: /dev/disk/by-partuuid/f9d099ff-d7b4-4d9a-9219-a952834c6f16
         File: └─/EFI/BOOT/BOOTX64.EFI

Boot Loader Binaries:
          ESP: /boot
         File: └─/EFI/systemd/systemd-bootx64.efi (systemd-boot 227)
         File: └─/EFI/BOOT/BOOTX64.EFI (systemd-boot 227)

Boot Loader Entries in EFI Variables:
        Title: UEFI OS
           ID: 0x0001
       Status: active, boot-order
    Partition: /dev/disk/by-partuuid/f9d099ff-d7b4-4d9a-9219-a952834c6f16
         File: └─/EFI/BOOT/BOOTX64.EFI

Default Boot Entry:
        title: Arch Linux
        linux: /vmlinuz-linux
       initrd: /initramfs-linux.img
      options: root=/dev/sda3 rw

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