[PLUG] flushing buffers?

Denis Heidtmann denis.heidtmann at gmail.com
Thu Jan 6 18:21:29 UTC 2011


On Thu, Jan 6, 2011 at 10:00 AM, Larry Brigman <larry.brigman at gmail.com>wrote:

> On Thu, Jan 6, 2011 at 9:56 AM, Denis Heidtmann
> <denis.heidtmann at gmail.com> wrote:
> > I am writing a little script to record the battery voltage v.s. time.  I
> > want to run it until the system shuts down due to low voltage.  Is it
> > reasonable to expect that the system will write the file buffer to the
> disk
> > prior to shutdown?  If not, what is a reasonable way to handle the
> problem?
> >  The system is ubuntu 10.04, the hardware is an ASU eee pc 900.
>
> If the system does it's own monitoring to do the shutdown then you
> will need a signal
> handler to catch the shutdown and/or term signal to go record record a
> reading and flush your buffers.
>

The system does the shutdown.  You are saying that the system will NOT
bother with dirty buffers; that if the system shuts down due to running out
of battery power any applications running are on their own.

This may explain a failure I had with this machine shortly after I received
it:  I ran it 'till it shut down.  When it came back up the some parts of X
were hosed.  There are other explanations for the failure, but this may top
the list if in fact the system behaves as you say.

I will have a bash loop running.  All I would need to do is force a write to
the disk in the loop as it nears the shutdown voltage.  How do I force a
write?

Thanks,
-Denis



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