RE: [SSI-users] Cluster strange boot behaviour

[Walker, B. J <bru...@hp...>]

The node monitoring is done over UDP so dropping tcp 900 etc. just hangs =
all other OpenSSI traffic, which will turn into hung processes =
(particuarly things like ps, that need to talk to all nodes).  I would =
expect that if you powered off node 3, the rest of the cluster would be =
just fine.  We probably should monitor the OpenSSI connections and fail =
more gracefully when one of the connections dies (that could be quite =
awhile with tcp timeouts), but otherwise I'm not sure there is a bug =
demonstrated here.

High load on the interconnect or on any node could slow down other nodes =
but as long as the node is not kicked out of the cluster, things should =
continue.  If, in normal operations (without special iptables calls), =
you get hangs, we may have something to debug.  Netdump is the preferred =
way to do that but working thru kdb is possible as well.   Having a test =
case that causes the hang (so we can reproduce and debug) is of course =
the best way to resolve.

Bruce

>=20
> 2/
> iptables -I INPUT 1 -p tcp -m multiport --ports 900,902 -j DROP
> This drops all Open-SSI related links from node3 to the init one
> (node1). =20
> node3 is still reachable via the ping command from node1. After a few
> seconds node1 hangs as described previously. Not any new=20
> process can be
> launched.
> Reboot all the cluster.
>=20
>=20
> I suppose these ports (900 and 902) are used to communicate=20
> between each
> node (I didn't see anything in the docs, I didn't read all=20
> mailling lists)
> But I do not belive this could be a strange behaviour. This may be a
> bug?
>=20
> I think when init node runs high load, networks should lag then damage
> all slave nodes. I'm not sure but this is what I saw.
>=20
> Note I use the stable openssi release (1.2.0) on a debian system (just
> read the docs).
> Mybe this had been fixed in the development version
>=20
> Next week I should test with 2 init nodes using LVS.
>=20
> Regards
>=20
> --=20
> Sebastien J. Gross
>=20
>=20
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>=20