Multiple subnets and lan failover in MCSG

[Steve Lewis]

I have a two-node cluster with 3 packages, each package on a separate subnet / interface card. The subnets have no routing to each other, except that each interface can see the other server on every subnet. So if a node gets powered off there would be no routing between subnets.

Currently there is no failover lan card.
Can somebody confirm to me what would happen if a package's lan interface card went down. Should it switch (only) that package over?

Secondly, in ServiceGuard, if you have a spare interface card, does it have to be able to take over any interface which goes down? For instance, if I install 3 spare interfaces, leave them unconfigured and plug one into each subnet, will it automatically failover to the correct interface card?

Does the topology have to route everything to everything in order for lan interface failover to work?

[Michael Steele_2]

Please attach :

# cmscancl -n nodeA -o /tmp/out_file

Regarding: "...Currently there is no failover lan card..."

No heartbeat means failover, reboot but no restart of cluster. No LAN, no cluster.

Regarding "... will it automatically failover to the correct interface card? ..."

Need to see your 'cmscancl' output. All of this is determined with 'cmquerycl' at initial cluster configuration. At this time all avail. LAN's are designated. There designations will be in the 'cmscancl' file which gathers its info. from the cluster.

Regarding "..everything to everything...". Qualification is determined with MAC addresses, LINKLOOP and called by cmquerycl. Again, this will be indicated in the 'cmscancl' output.

[Jeff Schussele · Accepted solution]

Hi Steve,

1) Yes - If that pkg's NIC fails only that pkg should failover. If more than one pkg uses that NIC then they all would fail over.

2) The failover is determined by NIC order in the cluster ascii file i.e. the standby NIC designated immediately after the stationary IP will be the NIC failed over to.

HTH,
Jeff

[melvyn burnard]

The package manager will only switch packages on a failed subnet when htat package has been configured to monitor the subnet, i.e. htere is an entry in hte package configuration file for that subnet.
If the other two packages are NOT monitoring that subnet, they will not be switched, as nothing has happened that they need to be woried about.

As for standby cards, you can have one card acting as a standby for many primary cards, but htis is not the best solution, as it means if one lan were to fail, your standby gets used, and htere are no more standby lans. Also, all lans hten have to be able to communicate to each other at LinkLEvel or DLPI level.

The better solution is to have a dedicated standby per primary lan, but hten htis costs money, an duses i/o space in system chassis, which you sometimes just don't have.

[Steve Lewis]

Thanks for the reply. Sorry, can't attach anything now, I am at a different customer at the moment.

The heartbeat goes over every interface, plus an extra (4th) network reserved for heartbeats.

Unfortunately I haven't been to this customer before and haven't been able to test lan failover and see what happens when I unplug a cable from each, which I why I asked the question. I have no evidence of anyone's previous test results either which is an issue.

Its also a production system so I am not going to try unplugging stuff during up-time.