[Linux-cluster] heartbeat

Dirk H. Schulz dirk.schulz at kinzesberg.de
Tue Feb 2 07:12:32 UTC 2010

Ed Sanborn schrieb:
> I am intrigued by this thread. I am using RH Advanced Platform version 
> 5.2. I have an 8-node cluster
> running on an IBM Bladecenter. For those that may not be familiar with 
> the IBM Bladecenter the blades have 2 NICs
> on them and the Bladecenter chassis has a Nortel switch that the NIC’s 
> connect to. I am using both NIC’s plugged
> into two segments of my LAN. One of them is being used for the 
> multicast heartbeat traffic. It works BUT occasionally
> my network has serious disruptions due to this being a 
> telecommunications company and the engineers are
> always doing something to loop the network and/or saturate the network 
> with broadcasts taking down the
> subnet that my heartbeat traffic is on. Sometimes when this happens 
> the network is so bad
> that the multicast traffic is affected and I lose quorum on the 
> cluster. Once I fix the network problem I need
> to restart each node to get the cluster back up and running. Not good 
> and not the correct design.
> I would love to NOT use a public NIC for the multicast/heartbeat 
> traffic. I tried to setup virtual interfaces and
> VLAN those in the Nortel switch and moving the multicast/heartbeat 
> traffic over to them, leaving the 2 NICS on the original LAN segments 
> they were on but even with IBM assistance we were unsuccessful. Does 
> anyone have any experience
> with this? I want to do this to truly isolate the heartbeat network to 
> eliminate any possibility for network congestion
> taking down the cluster and also because I do not want the multicast 
> traffic pumped all over the LAN.

What I do not understand at the moment: If you can afford to restrict 
one of every blade's two interfaces to cluster communication, why don't 
you put them into a VLAN (the real interfaces, not virtual ones) and see 
to it that the VLAN has not connection to any outside network?
Then the engineers would have no means of flooding your cluster 
communication subnet.

> Thanks,
> Ed
> (978) 210-9855
> *From:* linux-cluster-bounces at redhat.com 
> [mailto:linux-cluster-bounces at redhat.com] *On Behalf Of *Kumar, Ashish
> *Sent:* Monday, February 01, 2010 12:53 PM
> *To:* Fagnon Raymond; linux clustering
> *Subject:* Re: [Linux-cluster] heartbeat
>     I don’t have any nics that I can dedicate for a cross over cable
>     for heartbeat so I was thinking I could use the serial or the
>     network itself. Is it possible to just use the primary interface
>     for heartbeat since it is my understanding it is nothing more than
>     a ping.
> You don't need to dedicate a NIC for heartbeat with Red Hat Cluster. 
> Unlike Linux-HA, RHCS makes use of multicast to communicate with other 
> nodes. The multicast IP address is assigned by RHCS automatically, so 
> you don't need to do any special configuration.
> Please have a look at this: 
> http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Cluster_Administration/s1-multicast-considerations-CA.html
> For setup instructions, check this: 
> http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Cluster_Administration/s1-general-prop-conga-CA.html 
> - Section 3 deals with Multicast address settings
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