Creating a linux (redhat) core with sysrq-c doesn't work with UCS

[caroline.rasmussen]

I am trying to get a core dump from my Linux server running on a blade in a UCS however I can not get the OS to catch the sysrq-c.

The OS is hanging and the only option to get it back is a hard reset in the UCS console.

I can make the sysrq-c work on a standalone server.

I have tried to use the defined Macros for sysrq and alt-sysrq but the system doesn't seem to pick them up.

I tried to create a new macro however when I type in the box it never states sysrq. It shows print screen.

The only other computer I can work from is a MAC and doesn't have sysrq.

Does anyone know how to send sysrq-c to the console on a booting UCS blade?

Thanks in advance for any help.

Caroline

[Manish Tandon]

Caroline

Not sure if it will work as I have not personally tried it but did you try "Pass all keystrokes to target" in the KVM i.e under Tools/Session Options.

If you are in full screen mode it does it too.

Thanks

--Manish

[caroline.rasmussen]

Thanks for the reminder about the pass all keystokes.

This is working now by using the web browser with the KVM console launcher. I was going through the UCS GUI and accessing the console and had this checked before. I switched to the KVM but forgot to check it. Once I saw you post reminding me to check the pass all keystokes, the server echos that it received the commands to produce a core dump. The UCS GUI console still doesn't work for me. And creating a Macro with sysrq doesn't work either which means I can't do anything from a Mac. But this is progress. Again thanks for the help!!!

Caroline

[marcurry]

Hi Caroline,

Have to ask...are you sure the sysrq mechanism is enabled?

To enable it:

echo 1 > /proc/sys/kernel/sysrq

(For it to persist reboots, add the following line to /etc/sysctl.conf:  kernel.sysrq = 1)

Once you are sure its been enabled, try this other way (doesn't require any Ctrl/Alt keystroke sequences, or even a sysrq key) to invoke the sysrq mechanism and cause a core dump:

echo c > /proc/sysrq-trigger

Does that work?

-Marc

[caroline.rasmussen]

Yes those worked. However the system hangs which means I can't force a core dump with the echo c > /proc/sysrq-trigger. The only way so far to get the server to respond is sending a hard reset in the console. I also confirmed with support that I'm stuck with the sysrq during boot. Thanks for the response.

Caroline