re[2]: Clusterwide pids

[Greg Freemyer <freemyer@NorcrossGroup.com>]

 >>  Lars Marowsky-Bree writes:
 >>  >    "Albert D. Cahalan" <acahalan@cs.uml.edu> said:

 >>  >> How about this: when a node boots, pass it a PID range.
 >>  >
 >>  > This leaves us with the chicken and egg problem - how do you
 >>  > boot a node which is - at the time of boot - unable to contact
 >>  > the cluster?

 >>  "Albert D. Cahalan" <acahalan@cs.uml.edu> said:
 >>  You don't. It is a mistake to design for this perversion.
 >>  Do you, or do you not want a shared PID space? Make up your
 >>  mind about this. You don't run an SMP system as multiple
 >>  uniprocessor systems, then suddenly decide that you want SMP!

This may be good discussion point for the Ottawa meeting.  (No I won't be there.)

I have to agree that in order to get a shared PID space, it seems best to do it right off the bat.

I am most familiar with TruClusters from Compaq, and that is what they do.

If you must boot a TruCluster node, or set of nodes, without having quoram, then you have a separate diagnostic boot process you can manually use to override the quarom value.

I don't have the details handy, but effectively it is like:

    boot kernel -flags quoram_overide=n

Where n becomes your new quoram value for this one boot.

It is not typically used, but, for instance, if you have a 5 node cluster and 3 of the nodes die, you need a way to get the cluster back operational.

Greg Freemyer
Internet Engineer
Deployment and Integration Specialist
The Norcross Group
www.NorcrossGroup.com


Linux-cluster: generic cluster infrastructure for Linux
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