[DRBD-user] drbd & multicast?

[Volodymyr Litovka]

Hi Gianni,

On 08.04.2020 17:38, Gianni Milo wrote:
> 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.


Exactly. This is why multicast propagation, which can decrease PPS twice
[on particular node], can be kind of a silver bullet :-)


--
Volodymyr Litovka
   "Vision without Execution is Hallucination." -- Thomas Edison

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