[DRBD-user] drbd & multicast?

[Gianni Milo]

Hello,


> - in 1st case (originator is "disk" node) : about 1Gbps on receiving host
> - in 2nd case (originator is "diskless" node) : about 500Mbps on every of
> receiving hosts
>
> From what I see I conclude, that in 1st case (originator is "disk" node)
> the single copy of replicated data travels through network, while in 2nd
> case (originator is "diskless" node) there are two copies travel through
> network.
>

My understanding is the following...

- If you have 3 nodes, 2 of them Diskful (A,B) and 1 Diskless (C), then if
Primary is A or B, then there will be *one* write stream over the the
network (either from A -> B or B -> A), reads will be served locally on
each Diskful Primary node (if load-balancing is enabled also over the
network). Node C is ignored in this case.
  If the Primary is the 3rd (Diskless) node (C), then there will be *two*
write streams going through the network (C -> A,B) and possibly 2 read
streams depending if the load-balancing option is enabled or not. This is
probably the scenario you mentioned.

- If you have 3 (A,B,C) nodes and all of them are Diskful, then when any of
those nodes is in Primary mode there will be *two* write streams going
through the network(A  -> B,C or B -> A,C or C -> A,B) reads will be served
locally on each Primary node (if load-balancing is enabled also over the
network). This is probably the scenario that Robert mentioned.

I cannot comment on multicast and if it can implemented in DRBD though... :)

G.
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