Wait, SMACK does not use GMS, so how can you use GMS ?
SMACK is really 2 things (and maybe should be just 1). It has a simple group membership protocol
which (as far as we could tell) is full of holes and we are not using. We have: manage_channel_view=false
What SMACK gives us is multicast retransmits -- i.e. UNICAST for multicast packets. It keeps track of
who is talking SMACK to it (we had a lot of fun with the name) and then if it doesn't get an ACK from
someone, it will retransmit a multicast packet to the missing remote(s) using unicast.
Really, SMACK should be converted to RETRANSMIT for both unicast and multicast, but tearing that out
of UNICAST (which is doing 2 other things) would be hard.
Bela Ban wrote:
Interesting, in my perf experiments I've not seen high drop rates.
I suspect that when you have all machines plugged into one switch, they are very rare. But we have a reasonably complicated network topology with a lot of inner firewalls that have fragmentation and other transit tables which seem to cut the tops off of bursts dramatically. We see relatively few retransmits as well but without SMACK, these used to be lost data that was never recovered.