kdump not writing any vmcore

[Gallus]

Hello

What can be any reasons why kdump isn't writing vmcore file in
/var/crash/[date] directory? I have a box on which Kexec is property
configured: /etc/init.d/kdump status shows: "Kdump is operational".
There is no message like: "disabling kdump" in dmesg. Instead, there
are messages: "kdump: kexec: loaded kdump kernel" and "kdump: started
up".

After the random system-wide error occurs, kdump reacts correctly. New
kernel is started, and there are messages like: "Memory for crash
kernel (0x0 to 0x0) notwithin permissible range" (this is correct,
secondary kernel starts with different kernel command line, without
the crashkernel option, because it doesn't load any third kernel, as
we know) and "disabling kdump". But, there is no message: "kdump:
saved a vmcore to /var/crash/*" and no vmcore is saved.

When I tested exactly the same box with manually triggered system
crash (echo c >/proc/sysrq....), everything was the same except that
the "kdump: saved a vmcore to /var/crash/*" was emitted and the vmcore
was saved.

Regards,
Gallus