[Udpcast] poweroff not doing the job

Donald Teed dteed at artistic.ca
Thu Jul 15 17:14:10 CEST 2004

There is no shutdown command in busybox.  I don't know if
a statically compiled one from some other Linux would
do the same job.  I doubt it would match the needs
of the busybox/isolinux environment.

Our notebooks have 512 MB of RAM on board, and one
curious feature of udpcast imaging is that the udpcast sender
is disconnected when there is still about 5 GB of disk
to be written on the client/receiver.  It continues
writing from highly compressed zeros in RAM.

I joked with the production manager that if I got shutdown
to work, they could pack up the notebooks as soon as the
server disconnected and have them finish writing
from memory to disk while packed up on the shelf.
That could save about 5 minutes from the 30 minute job of
writing a 40 GB drive.

I guess my concern is for any few seconds of timing that
might be required for the disk cache to finish writing.
I recall there was a Windows there was a patch to deal
with allowing for the larger disk cache to do this on
Windows shutdown.  I don't know if "sleep 5" would do
the same or it needs 10, 15 or whatever.

--Donald Teed

On Thu, 15 Jul 2004, Felix Rauch wrote:

> On Wed, 14 Jul 2004, Donald Teed wrote:
> [...]
> > In the case of nothing being mounted, is there any potential
> > for damage to the client system by powering off this way inside
> > udpreceiver.post?
> If you are cloning directly to a hard-disk partition, there might (as
> far as I know) still be some blocks in the buffer cache that have not
> been written to disk (I assume that your apm command will halt the
> machine immediately, but I could be wrong).
> Alternatively, you could either first issue a "sync" command before
> halting the machine, or then shutdown the machine by executing the
> "shutdown" command with the proper arguments (like "-h" or "-P").
> - Felix

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