Open Stack

> >
> > Cool. I like this a good bit better as it avoids the reboot. Still, this is a rather
> large amount of data to copy around if I'm only changing a single file in Nova.
> >
> 
> I think in most cases transfer cost is worth it to know you're deploying what
> you tested. Also it is pretty easy to just do this optimization but still be
> rsyncing the contents of the image. Instead of downloading the whole thing
> we could have a box expose the mounted image via rsync and then all of the
> machines can just rsync changes. Also rsync has a batch mode where if you
> know for sure the end-state of machines you can pre-calculate that rsync and
> just ship that. Lots of optimization possible that will work fine in your just-
> update-one-file scenario.
> 
> But really, how much does downtime cost? How much do 10Gb NICs and
> switches cost?
> 

It's not as simple as just saying "buy better hardware" (although I do have a vested interest in that approach ;-)  - on a compute node the Network and Disk bandwidth is already doing useful work for paying customers.   The more overhead you put into that for updates, the more disruptive it becomes.

Phil