Re: checkpoint/restart milestone 1

[David Leimbach <leimy2k@xxxxxxx>]

MPI programs that run on clusters can have Fault Tolerance
in the form of checkpoint/restart.  This technology has been around
for a little bit but I don't think I have seen it at a general 
application
level before :).

I guess I am just pointing out that this sort of thing can be done
in a distributed manner.



> >     Kip, could you brief us on what this `checkpoint/restart' stuff
> >     exactly means?  I did not go to the Con, so I my guess is that
> >     this is like a software suspend kind of a thing, where the state
> >     of the system is saved, and it can be later resumed in the exact
> >     condition -- although I maybe wrong. :-)
>
> You're right, except its only at the application level, not the whole
> system.
>
> I'll give you an example:
> You have a compute-bound program that can run for weeks. The program,
> like many scientific applications was not well structured, i.e. it has
> a lot of implicit state sitting around in various globals and statics
> here and there. Hence, having the application programmer save its state
> is out of the question. However, you don't trust your hardware, so 
> you'd
> like to be able checkpoint the program in an application-independent
> way. This provides you with functionality for doing that. So if your
> program/computer crashes the program can just restart from the last 
> time
> it did a checkpoint.
>
> This could also be useful for debugging as well. If you have an
> application that starts doing something weird, you can just checkpoint
> it and send the checkpoint off to the developer.
>
>
> 				-Kip