> > What about the system save-state that SCO uses to recover from UPS initiated
> > shutdown? They write out the machine state into the swap partition.
> > When you restart your system, it picks up right where it left off. Nice.
> >
> > I have run an application which used over 300Mb virtual memory - wonder
> > what the SCO box would have done with that beast <distributed simulation>.
>
> The big problem with freezing processes or machine state and restoring
> it later is that the context gets partially lost like non-local network
> connections. Some code dies because time suddently warps. Or where
> to position file pointers when restoring a process? This is usually
> trivial when the file hasn't changed since taking the snapshot but
> can get very hairy otherwise.
>
> There is some software on the market for IRIX (Hibernator II by Softways)
> which can handle many of the problems involved gracefully but a general
> solutions isn't possible. Software which needs a nontrivial restoration
> process will have to handle that at least in part itself because neither
> the kernel nor other software can handle that perfectly.
>
Most processes should be able to deal with this... After all, you can
usually suspend any process for a few seconds without any ill effects. Any
properly written program that deals with remote items that it has no
control over will realize that they can and will die, and will know how to
restart the connection to them.