Canonical Voices

Posts tagged with 'crashdc'


crashdc : going Beta

That’s it ! crashdc is now officially beta software.

I just uploaded the 0.6-1 bits on the server which will be the official first fully functional release.

I’m also doing a presentation at Solution Linux 2010 tomorrow at 2pm.

So go ahead and download, test and bring back your results.

Read more

An example of crashdc output

Quick post to tell you that I have uploaded an example of the output that crashdc produces. It is using the newly developped BASIC mode (output from an ADVANCED mode is too big to post here).

You can view it here :

Read more

crashdc : An update

It’s been a while since I haven’t posted about crashdc.  Not that nothing happened, just that I didn’t get to it.

First of all, the development tree is now public and you can see it here :

I had to wait for my employer to allow me to contribute crashdc to the public so it took a little while to get done. During that process, I had to produce architectural diagrams that might be of some interest so I am posting them here.

For instance, this diagram shows how crashdc fits into a normal system installed and configured with kdump.  This is the automated way of using crashdc which can also be invoked from the command line.

Architectural diagram of crashdc

Architectural diagram of crashdc

In this one, you will find a high level flowchart of crashdc’s functionalities.

crashdc's flowchart

crashdc's flowchart

It highlights how crashdc works internally.

Currently, the specifics of the command lists (using built-in or custom list) is not implemented. I’m finishing testing of crashdc on all delivered kernels of RHEL5, SLES10 and SLES11 on both i386 and x86_64 before going into this.

Hopefully, I will have something close to ‘beta’ flavor by end of february if my daytime work allows for it. I’ll keep you posted.

Read more

crashdc : The architecture

So you might want to know more about how crashdc is organized.  Well here are a few pointers.

crashdc is a shell script that is called from a kdump mechanism which is triggered when a vmcore dump file gets created. The file it creates is named crash-data-{date}.txt Unfortunately (for me), this mechanism is different in all three implementation that crashdc supports :

  • RHEL5   : kdump_post

It can also be run interactively on an existing vmcore to generate the crash-data-{date}.txt file afterward.

I will try to go in a little more details about each of the automated mechanisms. But it is important to know that crashdc itself is identical for all three distributions. The only thing that changes is the run-crashdc-{distro}.sh shell that is executed by each one of those mechanisms.

RHEL5′s kdump_post

This is the most straightforward. When uncommented, the kdump_post variable in /etc/sysconfig/kdump is setup to run the /var/crash/script/ script. This script is in fact a symlink to /usr/bin/ which takes charge of finding vmcore’s location, and to invoke crashdc.

SLES10′s implementation is more complex. When KDUMP_TRANSFER is defined, the command it invokes becomes responsible for reading vmcore’s data out of /proc/vmcore and to store in in a file. Otherwise, it is the save_core shell function from /etc/init.d/kdump that does that.

So /usr/bin/ has an identical copy of the save_core function (yes I copied it) that will copy the vmcore file. The rest of the script does the same thing than for RHEL5, which is to invoke crashdc with the appropriate parameters.

Once again, SLES11′s implementation is different.  When invoked from witihin the kexec environment, the script pointed to by KDUMP_POSTSCRIPT runs in an environment where the / file system is memory resident, and the real disk-based / file system is mounted in /root.  So the /usr/bin/ knows all so it is still able to invoke crashdc correctly.

Those three mechanisms are all KDUMP specific handles. This mean that they run right after a kernel panic, when the KDUMP kernel is running and before a reboot has been done.

Post Reboot processing
Some system administrators might not like the idea that unnecessary processing is done in that context. This is why one last script has been developped : /etc/init.d/crashdc This script can be used when the system reboots to its regular environment to generate the crash-data-{date}.txt file.

With this method, the crash-data-{date}.txt will only get created when the system reboots on the regular kernel.  The current limitation is that it will only process the latest vmcore created in order to avoid extra processing in case of multiple kernel panics.  Yet, there should be an option to manually process all vmcores where crash-data-{date}.txt has not been found.

Right now, this script only exists in my mind so there are chances that it might evolve quite a lot before it gets done.

So I hope that this brief post is clear enough to highlight the main mechanisms used by crashdc.

Read more


Sorry for those of you who are used to read me in french, but you will see appear here, from time to time, notes, posts and information about an opensource project that I’m working on : crashdc.

crashdc is a set of scripts to be used in conjunction with Dave Anderson’s crash tool. Without crash, crashdc is useless. With it, crashdc can automate data collection when a new kernel crash dump occurs.

Dave Anderson has kindly accepted to include crashdc in the crash package, so when crashdc will be ready, this is where you will be able to find it. I also created a sourceforge project for it called obviously crashdc, where you can find standalone bits and information about crashdc itself.

The Sf environment does not intend to ack as a parallel project, but just a place for me to host my development which itself will make its way to the crash rpm.

Right now, don’t look for the crashdc bits : they’re not available yet.  Being employed by a major computer constructor, I must first clear out the project internally so I can have the right to publicly distribute crashdc. This shoudln’t be too long. And since crashdc is mostly Alpha code right now, this would not bring you much to get it as it is.

So bear with me a little longer, and it should become available for a first round of testing soon.

Read more