[Gluster-devel] Multicast Support?

[Anand Avati]

> One other thing occurs to me - in cases where multicast isn't directly
> available, an externel helper/replicator would be equally useful for
> emulating a similar thing.
>
> For example, if I have 4 systems on 2Mb pipes (e.g. DSL) and have a system
> at a colo on a cheal all-I-can-eat 10Mb pipe, it would make sense for each
> machine to send it's writes ONLY to the colo-ed machine, which can then
> replicate the write to the 3 other systems. This means that systems on 2Mb
> pipes would still get 2Mb if write bandwidth. In the classic setup, they
> would only get (2/3)Mb of write bandwidth.
>
> I've been thinking about setting this up as 4 separate AFRs (each between
> one satellite node and the central node), but I am not sure whether writes
> would actually propagate. Can any of the devs hazard a guess as to what
> would happen? Would locking still work if each of the satellite nodes
> specifies the core replication node in it's AFR node list? The one problem
> with this that I can see is that the core node would also have to contain
> all the data - I cannot think of a way around this at the moment.
>
> Has anyone got any thoughts on this?

GlusterFS relies upon the transport being reliable. Using multicast
for reliable transfers is quite tricky and would need considerable
redesign of the current codebase atleast.

Avati