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

From: Daniel Phillips
Date: Wed Sep 01 2004 - 10:15:58 EST


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?

Regards,

Daniel
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