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Re: Random crashes that won't allow rebooting easily


On Thu, Apr 18, 2013 at 06:41:58AM +0100, Bill Harris wrote:
> I'm running an up-to-date Debian Squeeze 64-bit on a laptop.  It's usually been
> stable, as I might expect from Debian Stable.  From time to time, though, it
> freezes at seemingly random times.  I notice it mostly when I'm typing and the
> keyboard stops responding, but I'm not sure it always freezes while typing.  I
> can't do anything at that point, not even select a virtual console.

Sounds like hardware. Or low level software.  Any "fun" video drivers
on this laptop?

>From what you write, I'm not sure whether the freezes are fatal or
just temporary or a combination thereof.  I'm going to assume that
they are (mostly) temporary.

Does the mouse ever "freeze" ?

If you use terminals with blinking cursors: Is the blinking affected?
(or $DEITY forbid: open browser windows with animated adverts and
similar junk)

Does caps-lock turn the keyboard LED on/off?
> I can't find an Alt-SysReq key on the laptop keyboard to kill it
> semi-gracefully, so I kill it with the power button.  

Yes - Alt-SysReq is challenging on laptops. But not impossible.
Expect to use a lot of fingers.

Usually it's "Fn+something" (on my Dell: F10) just to do the "SysRq"
key, and then the trick was to *release* the Fn key (but not the SysRq
key) before hitting e.g. "I" - otherwise it got read a "numeric keypad
5".  That took a while to figure out.

> When I reboot, it usually boots partway and then freezes again.  It's almost
> always just after it's said it's starting gdm3, checking battery status, or
> starting ACPI.

Next time it happens: Try entering the BIOS and do "stuff". Not to
change things, but simply to see whether it also happens when *only*
the bios is running.  If so, then this would point to a hardware
problem, rather than a software problem.  I.e. a problem not related
to Linux.

If it fails to crash at this point, then the experiment is
inconclusive - the bios may simply fail to trigger it.

> Getting past that point is challenging.  I've tried disconnecting the power and
> taking out the battery, but that rarely helps.  What usually helps is to boot
> into Windows (W7, if it matters) and then shut down and boot into Debian.  
> Sometimes it seems to help to pull the battery for a bit, too.  Sometimes
> neither seem to help, and so I keep trying combinations until it reboots.

What you describe could be a case of $something overheating - once
things get hot, crashes become more frequent.  Until $something cools
down, and things seem to fix themselves.

Does it feel physically hot? Is the fan working overtime?

> Does that sound at all familiar?  If so, is there a solution (either to keep it
> from freezing or to recover more rapidly after freezing)?  What data (log file,
> I presume) do you need to help me find and fix the prroblem?

There may be entries written to the log files which never reach the
disk because of the crash.  If you have another server on the network,
you may benefit from sending the syslog to that server - rsyslog has
built-in facilities for this.

Hope this helps

Karl E. Jorgensen

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