[Linux-cluster] CMAN/DLM without SCTP

Pratik Mehta pvmpublic at gmail.com
Tue Feb 18 13:33:44 UTC 2014

I am trying to use a cluster with Pacemaker + CMAN on CentOS 6.4. The
application that runs on the cluster includes a userspace SCTP stack.
However CMAN loads dlm which loads the Linux kernel sctp module, which
interferes with the userspace SCTP.

I do not have any GFS/locking requirements on this cluster. I use a 2 node
cluster to failover a bunch of IP addresses.

I tried setting DLM_CONTROLD_OPTS="-r 0" and blacklisting sctp module.
Didn't help since dlm depends on sctp and cman loads dlm.

In /etc/init.d/cman:
errmsg=$( modprobe dlm 2>&1 ) || return 1
errmsg=$( modprobe lock_dlm 2>&1 ) || true

As a hack: I modified the cman service to not load dlm and lock_dlm. The
cluster seems working. However I do not know what additional functionality
was broken when I disabled these. Though a hack: I am eager to know if
someone sees an issue of running a production cluster with this.

Another options is to introduce a compile time flag in the DLM kernel
module to not use SCTP.

Is there any other way?

Thanks in advance
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