That's an odd thing to say, isn't it? Re-read my first sentence again,
carefully this time. If one can throw a process on another machine at will,
it becomes trivial to checkpoint, yes? Fault tolerance for free.
Jim Nance <jlnance@avanticorp.com> writes:
> On Tue, Sep 30, 1997 at 10:06:25PM -0500, Tall cool one wrote:
> > Personally, I don't have a real need for process migration, but I'd like
> > to see it because of what process migration would allow. The ability of
> > stopping a process in it's tracks, saving it to a core like file, rebooting
> > the machine, then restoring back the process comes to mind. The occasional
> > moving to another machine would be nice as well I suppose. I'm much less
> > interested in the "performance" hit I'd take, as I'd only need it
> > occasionally.
>
> Technically thats called checkpoint/restart. Its easier to do than process
> migration. The thorny issues are user space things like what happens when
> you are talking to another machine via a TCP/IP socket. The other machine
> has to know how to deal with you restarting the connection from a potentially
> different machine and making it look like it never went down. If you
> ingore these type of problems, things get considerably easier.
Okay, I'd like to see proccess migration, process checkpointing, and fault
tolerance (especially fault tolerance). Whatever makes you happy.
Typically I wouldn't need to migrate network applications, although it
could conceivably be possible with some sort of proxying. Not that I'd want
to implement it. =) Or perhaps the machines share the same IP's but have an
running agreement on what ports on which machines the IP's go to. Probably
could be done with local firewall rules. Need a userland daemon to keep the
"port-map" in sync though.
I'm the first to admit, that the above things are not really that
important to me, just neat and potentially useful. The process migration
thread just made me think about them and suggest potential other (simular)
uses for it.
- Steve
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