[Linux-cluster] dedicated heartbeat LAN and documentation

Riaan van Niekerk riaan at obsidian.co.za
Fri Jul 21 11:30:25 UTC 2006

sun sadm wrote:
> Hello colleague
> How to configure a dedicated LAN (for example eth3) as heartbeat? We
> don't wish heartbeat over public LAN.
> Second: the official  documentation (Red Hat Cluster Suite Configuring
> and Managing a Cluster) is very bad. Are there additional documents?
> Nico
Hi Nico

1 the heartbeat happens over the interface which carries the IP which 
resolves to the node names. There is no way to have another or an 
aditional heartbeat interfaces configured as was the case with 
clumanager in RHEL AS 2.1. Your best solution to have a redundant 
heartbeat interface (albeit over your primary/public interface) is to 
use channel bonding. Perhaps you can configure your nodes to communicate 
over the non-public LAN but have  VIPs and services running on the 
public LAN. I have never tried this, and we have decided to live with 
heartbeat over public LAN, using a non-default multicast address: cman 
sends heartbeat info every 5 seconds to (what we configured) 
or the broadcast address on port 6809. This traffic is minimal, to a 
non-standard port, and avoiding it over public LAN might be a major hassle.

note (aside): RHEL 2.1 had heartbeating capability over serial, 
non-public LAN and the primary LAN (as well as quorum partition 
communication), which lessened the impact of any of the other channels 
going down).

2 I have the following list of resources (apart from the official docs) 
for own internal use:

Project page

Cluster Suite, GFS project FAQ

Red Hat Cluster Suite NFS Cookbook

Indepth discussion on Failover domains

GFS page at DataCore (somewhat old, but still has information which 
might be useful)

GFS wiki (non-Red Hat maintained)

You are right, the official Cluster Suite documentation is definitely 
not what it should be. There are numerous bugzilla entries open against 
the docs. Upon enquiring about the state of Cluster Suite documentation 
with my Red Hat representative, he said that there is something in the 
works, but could not give me an ETA on when the docs will be 
re-released. The linux-cluster (this list) archives are definite your 
friend. You can also try #linux-cluster on irc.freenode.org, even though 
this channel has (IMHO) more developer than user activity.

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