On Sat, Jun 03, 2000 at 06:25:37PM +0100, James Sutherland wrote:
> On Sat, 3 Jun 2000, Bruce Guenter wrote:
> > On Sat, Jun 03, 2000 at 02:29:34PM +0100, James Sutherland wrote:
> > > This is, IMHO, quite an attractive idea: a fully hot-swappable system,
> > > where any failed component can be replaced without any downtime.
> >
> > And how do you plan on swapping out the motherboard that everything
> > connects into?
>
> Every "component" is mounted on a carrier board; this then connects to a
> pair of backplanes. Each individual component can, obviously, be replaced;
> you can also remove/disable one backplane at once without downtime.
>
> The next issue is to enable software upgrades without downtime. For
> applications, this can be done by installing the new version, then
> signalling the old version to "exec" the new one. (Apache can do something
> similar with configuration files already.) For a WWW server, for example,
> this can be done without dropping or refusing a single connection.
>
> The kernel itself would be harder, of course. Kernel modules could do
> something similar - just unload the old one and reload the new one, taking
> care to avoid anything trying to use the module in the mean time - leaving
> just the core code - memory management etc., which would be much more
> difficult.
Don't the HP RISC line have a feature kind of like that? I believe they are able to load a new kernel without a reboot or even downtime. IMHO, this sounds like a great idea, and would definitely be a "plus" for public relation encouragement. Also, the same case with the Hot Swappable CPU idea, this would be great for articles and reviews, (never mind the obvious practical benefits).
To the man that just wanted to add another box instead:
Just think of it this way, nearly everything that gets done in kernel development and added features, there is probably a better way to do it with another solution, but the ability to do it is what makes the difference. Look at Microsoft: supposedly, you can run a box with up to 32 CPUs with win2k maximus serveros(or whatever), but you could probably do a much better job with 32 seperate machines and proper load balancing, but 32 concurrent CPUs sure made them look nice in reviews. It's stuff like that (the nonsense, stupid things) that make the difference. Also, I sure wouldn't mind having the capacity to take out the second CPU on my box if one fails, or I just want to (I don't know the practicalities of this) upgrade it for that matter, but I'm sure big businesses using boxes like that sure would eat that feature like candy. It might even contributed to linux's reliable reputation. Just my .02.
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