nodes have only one network interface

[Arnulf Gercke]

Hi everybody,

is it possible to setup a two node hp-ux mc/sg cluster, if the nodes have only one ethernet interface?
Of course - this environment would be only for some internal testing.

[Mel Burslan · Accepted solution]

Even though I have never done it this way as it is against the HA subject matter because of the single point of failure, I do not see a reason why this should be a problem. SG does not have any harsh hardware requirements. You can pretty much run it on any two boxes which match the minimum HW configuration which is not too bad to start with anyway.

In a lab environment, it can do anything except testing for resiliency against network failures.

[Devesh Pant_1]

With a single NIC the whole purpose of high availability gets defeated. But since you are doing internal testing, it might be interesting to set it up with a single NIC - With the heartbeat and the traffic going through the same NIC
good luck
DP

[Brian Vance]

Serviceguard requires either two interfaces, or one interface and a serial connection (crossover). If the systems are close enough to connect together with a serial cable, you can set it up that way.

[RAC_1]

You can. While the whole purpose of using MCSG is to avoid SPOF, you can still do that.

you will have to use crossover cable for heartbeat.

Anil

[Duncan Edmonstone]

Will it work? Yes.

Is it supported? No.

I guess it depends very much on what you are trying to test. There's so much of serviceguards functionality that is dependent on networking that I don't know how many tests could be considered as 'representative'.

Of course if your just after a sandbox, then fine - just don't expect SG to behave the same as it will in a 'supported configuration'

HTH

Duncan

[Sudeesh]

Yes you can have such a setup. I have seen a few implimentations in HPUX 10.20/MCSG. Use a serial port connection for heartbeat.

Sudeesh

[Victor Fridyev]

Hi,

Such a cluster will work. I have some laboratories with two node clusters ( even one node SG). If you want to check package scripts, such a cluster is suitable, but if you like to demonstrate additional SG cluster features, you can have problems.

HTH

[Bob_Vance]

Yes. I have done this many times in a lab environment (to test package code).


1) Actually, a 2-node cluster with only one NIC in each *is* supported -- as long as you have a serial connection for additional heartbeat, as mentioned above. In event of a NIC failure, this allows the node with the good card to receive the packages, while the bad-NIC node is failed.

2) Use of a cross-over cable with ServiceGuard is deprecated. Anytime one node is down, the other node will see hardware errors. At least a cheap HUB should be used. Of course, in a one-NIC case, you would also have no client connection ;>)

3) Furthermore, a semantic quibble: Service Guard does not provide protection from SPOF -- High Availability design does that ;>) Service Guard is a component of a HA design and simply allows packages to run on other nodes when a problem occurs. Obviously, redundant storage connection are done all the time without SG. Even local NIC failover can be done without SG (e.g., with APA).

4) However, the above applies to a production environment.

In LAB, you can certainly have only one NIC -- and even not have a serial cable.


hth
bv

[Mahesh Kumar Malik]

Hi Arnulf

Yes, it is possible to setup a two node hp-ux mc/sg cluster, if the nodes have only one ethernet interface. You may use Serial ports for heartbeat monitoring

Regards
Mahesh

[Arnulf Gercke]

thank you all!

we did it this week in france -
and it worked pretty fine -
no serial cable for heartbeat is neccessary.