Re: Clusterwide pids

[Chris Wright <chris@wirex.com>]

* J . A . Magallon (jamagallon@able.es) wrote:
> 
> On 20010712 Chris Wright wrote:
> >* Albert D. Cahalan (acahalan@cs.uml.edu) wrote:
> >> Chris Wright writes:
> >> > * Albert D. Cahalan (acahalan@cs.uml.edu) wrote:
> >> >> 
> >> >> 1. boot the single node without joining the cluster
> >> >> 2. fix the node
> >> >> 3. reboot to join the cluster
> >> > 
> 
> Sure it has been talked about before, but I do not remember any conclussion.
> Which is the problem with booting like
> 
> linux nodeid=47
> 
> and let the cluster admin be sure there is no duplicate id ?
> Then node just boots and joins the cluster in user-space.

perhaps i'm misunderstanding.  albert mentioned booting into two separate
modes, a cluster mode and a non-cluster mode.  in the cluster mode,
you could certainly hardcode the node id as you mentioned.  of course,
some admins may prefer the transparency of getting the node id assigned
when the node joins the cluster, but that's another issue.  either way,
this does not seem to address the possbility of maintaining a single
boot mode that allows a machine to run local only processes (init, fsck
local volumes, etc.) without obtaining a cluster-wide unique pid from
the cluster.

i was simply asserting that there are some processes (even in an SSI
cluster) who should never run anywhere but the local node (hence the node
id 0, 127.0.0.1 analogy).

if i understand your suggestion, you are saying that the node should be
booted and able to run processes before it joins the cluster (otherwise
how would it join the cluster in user-space?).

i think the question is what does a common process space look like in
a cluster?  can it be segmented such that non-cluster processes and
cluster processes can co-exist uniquely in the pid space.  i assert this
is possible if you include the node id as part of the pid, and make a
special case (node_id == 0) for local only processes.

-chris

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