::scr Cesium

[Piers Cawley]

David Cantrell <david@cantrell.org.uk> writes:

> On Wed, Oct 31, 2001 at 02:53:23PM +0000, Piers Cawley wrote:
>> David Cantrell <david@cantrell.org.uk> writes:
>> > Riiiight. Without a multi processor box with some deep DEEP voodoo
>> > that won't be possible. You'd need to stop a processor, bring up the
>> > new kernel on that one, then stop all the others and bring up the
>> > new kernel on them. But there will be a point where you are running
>> > both kernels. And what of in-memory structures which change from one
>> > kernel to the next? Even in the mainframe world you have to down the
>> > machine to replace the most fundamental pieces of software.
>> Actually, there are/were Vax/VMS clusters with uptimes into double
>> digit years, that in their most recent incarnations were running an OS
>> that was a couple of major revision numbers higher than where they
>> started, and where none of the hardware in the cluster had been there
>> when the cluster started.
> 
> Clusters, however, let you down individual boxes in the cluster whilst
> still keeping the cluster running.  That is the whole point of a cluster
> after all!  But you can't upgrade VMS on a single box without downing the
> box at some point.

Indeed, but the beauty of the cluster was (unless my memory is playing
me up) that, to the user, it just looked like one machine.

-- 
Piers

   "It is a truth universally acknowledged that a language in
    possession of a rich syntax must be in need of a rewrite."
         -- Jane Austen?