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Re: inventory
--- Jeff Darcy <linuxguy@tambreet.com> wrote:
> > > I thought that in most HA clusters, each machine has a "true name" (&
> > > IP) that's unique and never changes, and then other names (& IP
> > > addresses) that are associated with services that move around when
> > > things fail? A single, unique hostname is still sufficient, and you
> > > can make them one byte. Then you don't have any need for an extension?
> > >
> > That is most common, yes. However, there is one example (with which I'm
> > familiar) that this is NOT the case: HACMP on AIX. All IP addresses are
> > migratable, there is no persistent node name for any machine.
>
> This was not true when I was working on HACMP. Each interface had a "boot
> address" that only it could use, in addition to one or more service
> addresses. When a node came up, it would use its boot address(es) to join
> the cluster, and then switch to its properly-assigned service address(es).
> Similarly, each node had a node name separate from all of its interface
> names, precisely to avoid the sorts of confusion we're talking about.
>
The issue, as I remember it, was that the boot addresses may not be present.
The specific case was the 'force down' then reintegrate. In that case, if the
adapters had their service addresses, those needed to be left active when HACMP
restarted and wanted to reintegrate.
As to the node name, you're right. I was too sloppily trying to combine too
many points. The specific point didn't deserve the generalization I gave it.
> Did these things change sometime after '95, did Phoenix undo a lot of our
> careful design, or is one of us misremembering?
Phoenix changed nothing about existing HACMP semantics. We had to adjust
Phoenix to account for this case. The above behavior was present when we first
needed to support HACMP semantics. This was around 1997/8, so I have no
knowledge of what, if any changes, occured in HACMP between 1995 and then.
=====
These have been the opinions of:
Peter R. Badovinatz -- (503)578-5530 (TL 775)
wombat@us.ibm.com/tabmowzo@yahoo.com
and in no way should be construed as official opinion of
IBM, Corp.
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Linux-cluster: generic cluster infrastructure for Linux
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