[Linux-cluster] New virtual synchrony API for the kernel: was Re: [Openais] New API in openais

Daniel Phillips phillips at redhat.com
Wed Sep 1 15:15:45 UTC 2004

Hi Steven,

(here's the rest of that message)

On Tuesday 31 August 2004 15:50, Steven Dake wrote:
> It would be useful for linux cluster developers for a common low
> level group communication API to be agreed upon by relevant clusters
> projects.  Without this approach, we may end up with several systems
> all using different cluster communication & membership mechanisms
> that are incompatible.

To be honest, this does look interesting, however could you help me on a 
few points:

  - Is there any evil IP we have to worry about with this?

  - Can I get a formal interface spec from AIS for this, without
    signing a license?

  - Have you got benchmarks available for control and normal messaging?

  - Have you looked at the barrier subsystem in sources.redhat.com/dlm?
    Could this be used as a primitive in implementing Virtual Synchrony?

  - Why would we need to worry about the AIS spec, in-kernel?  What
    would stop you from providing an interface that presented some
    kernel functionality to userspace, with the interface of your
    choice, presumably AIS?

  - Why isn't Virtual Synchrony overkill, since we don't attempt to
    deal with netsplits by allowing subclusters to continue to operate?

  - In what way would GFS benefit from using Virtual Synchrony in place
    of its current messaging algorithms?



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