Bug 605411

It looks like RHEL5 needs this as well, however I'll hold off on cloning until we have some feedback on the patch from FJ.

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This looks strange, if you really want to collect the core from a raw partition, why not just dump to a vmcore file instead of a raw partition? Neil, is this what 'raw XXX' is used for?

 

raw XXX causes the kdump initramfs to dump /proc/vmcore to a raw disk w/o the aid of any file system.

The patch above appears to recover such a dump, although I'm hesitant to take it in this form, as there is no guarantee that:
1) there will be space in /var/crash for such a dump
2) there is no guarantee that we know to need to use makedumpfile -R on the dump.

Thats part of the reason we require by hand dump recovery

it might be better to just indicate to the user that a dump is waiting for recovery on startup

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Dave, still waiting on feedback from FJ, as per comment 4.  Thanks!

(In reply to comment #4)

> raw XXX causes the kdump initramfs to dump /proc/vmcore to a raw disk w/o the
> aid of any file system.
> 
> The patch above appears to recover such a dump, although I'm hesitant to take
> it in this form, as there is no guarantee that:
> 1) there will be space in /var/crash for such a dump

You never know that, the same situation exists if you dump straight into a partition in the first place. But AFAICT many customers use DUMPLEVEL 31 anyway, so the space requirements are moderate.

mkdumprd issues a warning if dump is configured to write to a file system partition that it considers too small to capture the dump (well, IMO mkdumprd's required size estimate is pretty rough). The same could be done for raw partitions.

> 2) there is no guarantee that we know to need to use makedumpfile -R on the
> dump.

I don't understand what you mean here. To my understanding makedumpfile -R will be required because mkdumprd either uses dd or makedumpfile -F, which both produce "flat" format.

> Thats part of the reason we require by hand dump recovery
> 
> it might be better to just indicate to the user that a dump is waiting for
> recovery on startup    

That should be very clearly documented and indicated, otherwise the risk of loosing a dump in a critical situation is very high.

Raw dumping is desirable in many environments because the chance for failure is lower than in all other cases. Besides, it behaves like diskdump in RHEL3/RHEL4 and many users like this behavior.

fine.

lowering priority/severity, since this has not been accepted for 6.0, and isn't causing any real failures currently.

Changing into a 6.1 feature request.

So, besides this patch, we also need to:

1) warn if the partition is too small
2) document that a dump is waiting for recovery on startup in this case.

Am I missing anything?

With dump compression, how do you know if the partition is too small? With the terabyte memory era approaching, requiring the dump partition to be the same size as physical memory is getting unrealistic.

Amerigo, I think all we need to do here honestly is just check to see if a core exits and try to recover it as the attached patch does.  Lets not try get too fancy with it.

Tested with latest build:
=====================================================
[root@ibm-js22-07 ~]# rpm -q kernel kexec-tools
kernel-2.6.32-122.el6.ppc64
kexec-tools-2.0.0-171.el6.ppc64
[root@ibm-js22-07 ~]# tail /etc/kdump.conf 
#kdump_post /var/crash/scripts/kdump-post.sh
#extra_bins /usr/bin/lftp
#disk_timeout 30
#extra_modules gfs2
#options modulename options
#default shell

raw /dev/sda3
core_collector makedumpfile -c --message-level 1 -d 31
default shell
[root@ibm-js22-07 ~]# touch /etc/kdump.conf 
[root@ibm-js22-07 ~]# service kdump restart
Stopping kdump:[  OK  ]
Detected change(s) the following file(s):

  /etc/kdump.conf
Rebuilding /boot/initrd-2.6.32-122.el6.ppc64kdump.img
Starting kdump:[  OK  ]
[root@ibm-js22-07 ~]# echo c > /proc/sysrq-trigger
--------------------------------------------------------------------------------------
mdadm: No arrays found in config file or automatically
Free memory/Total memory (free %): 150208 / 231296 ( 64.9419 )
Scanning logical volumes
  Reading all physical volumes.  This may take a while...
  Found volume group "vg_ibmjs2207" using metadata type lvm2
Activating logical volumes
  2 logical volume(s) in volume group "vg_ibmjs2207" now active
Free memory/Total memory (free %): 149312 / 231296 ( 64.5545 )
Saving to partition /dev/sda3
Free memory/Total memory (free %): 149312 / 231296 ( 64.5545 )
Copying data                       : [100 %] 
Saving core complete
Restarting system.
......

Starting RPC idmapd: [  OK  ]
Dump saved to /var/crash/2011-03-18-05:46/vmcore
Starting kdump:[  OK  ]
......
[root@ibm-js22-07 ~]# ls -lsh /var/crash/2011-03-18-05\:46/
total 28M
28M -rw-------. 1 root root 28M Mar 18 05:46 vmcore

Change status to VERIFIED.

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2011-0736.html