service guard question

[bond007]

Hi All,

In a 2 node cluster which has 1 NIC for data network and HEARTBEAT is configured thru serial port,What would happen if the serial line(HB) fails ?

Will the HB go thru the DATA network itself or the cluster will fail/reform ?

Thanks in advance

Bond

[Adisuria Wangsadinata_1 · Accepted solution]

Hi Bond,

If the serial line (for HeartBeat) fails, the package will be transfer to the secondary node. It's similar happened when the primary node fails.

Since you choose serial line as your HB, the HB will not go thru the DATA network.

The HB is needed to check the nodes among the cluster, so on your configuration (2 node cluster) if the HB fails, the package will be transfer to the secondary nodes.

PS : with 1 NIC, there's no HA on your cluster.

Hope this information can help you.

Cheers,
AW

[Patrick Wallek]

If the heartbeat fails (your serial line) then each node will tray to grab the lock disk, or if you use a quorum server the nodes will query it. The node that loses the quorum will TOC and the cluster will reform on the other node.

[Jakes Louw]

Yes, if there is only one HB interface, the cluster will panic and will attempt to reform.

[melvyn burnard]

Are you saying that you want to have the heartbeat ONLY on the serial link?
If so, this is not possible, as the serial heartbeat is only a partial heartbeat.
You MUST have the heartbeat on the LAN card as well.
In this case, if the serial link fails, nothing happens, but if the LAN heartbeat fails, then the serial link is used to decide which host still has a valid network, and forces the other to TOC.

It is used only for that purpose.
As an aside, HP are looking at obsoleting the serial heartebat as of the next release of Serviceguard.

[Steve Lewis]

I agree with Melvyn on this one. Firstly it won't work unless you add the heartbeat on the main lan as well.

As a general point, it makes sense to send the heartbeat down multiple interfaces. It is very light traffic and can be used to avoid unneccessary TOCs. I put heartbeat on all configured lans that can communicate node to node.

You should also tune your heartbeat timeout value.

[Chan 007]

Bond,

The cluster will loose the quorum and both will TOC (as both will try to capture the cluster lock. Once TOC is complete it will restart the cluster.

Chan

[Sivakumar TS]

Dear Bond,

The cluster would reform since the HB is lost, and both the nodes will try to own the Cluster lock.

With Regards,

Siva.

[Geoff Wild]

You can't have HB on serial only...

If you lose the heartbeat - you lose the cluster - there will be a TOC (transfer of control) on the server that does NOT get the cluster lock disk - if your production happens to NOT get it - then it will come down - hard....

There is no harm configuring multiple HB networks and having backup over say the primary interfaces...

Rgds...Geoff

[Kent Ostby]

You need to have a minimum of one NIC running heartbeat traffic and for any kind of redundancy, you really should put it on two actual networks.

The only thing that the serial buys you is that if you have a two node cluster and one box loses its network, the serial will help keep up the box that has the good network.