Re: [PATCH 0/7] dlm: overview

From: David Lang
Date: Thu Apr 28 2005 - 19:36:55 EST

On Thu, 28 Apr 2005, Lars Marowsky-Bree wrote:

On 2005-04-27T18:38:18, Daniel Phillips <phillips@xxxxxxxxx> wrote:

Uuids's at this level are inherently bogus, unless of course you have more
than 2**32 cluster nodes. I don't know about you, but I do not have even
half that many nodes over here.

This is not quite the argument. With that argument, 16 bit would be
fine. And even then, I'd call you guilty of causing my lights to flicker

The argument about UUIDs goes a bit beyond that: No admin needed to
assign them; they can stay the same even if clusters/clusters merge (in
theory); they can be used for inter-cluster addressing too, because they
aren't just unique within a single cluster (think clusters of clusters,
grids etc, whatever the topology), and finally, UUID is a big enough
blob to put all other identifiers in, be it a two bit node id, a
nodename, 32bit IPv4 address or a 128bit IPv6.

This piece is important. It defines one of the fundamental objects in
the API.

I recommend you read up on the discussions on the OCF list on this; this
has probably been one of the hottest arguments.

how is this UUID that doesn't need to be touched by an admin, and will always work in all possible networks (including insane things like backup servers configured with the same name and IP address as the primary with NAT between them to allow them to communicate) generated?

there are a lot of software packages out there that could make use of this.

David Lang
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