[DRBD-user] Restarting IPtables caused split-brain and OCFS2 corruption?

Andreas Hofmeister andi at collax.com
Tue May 17 21:12:33 CEST 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On 17.05.2011 18:19, Herman wrote:
>
> I made a change to IPTables, and did a "service iptables restart", and 
> next thing I knew, I had a split brain.

I would guess that  the RHEL FW setup flushes the connection tracking 
tables and has a default drop (or reject) rule.

  This would cause DRBDs TCP connections to time out eventually. Also, 
neither OCFS nor DLM react kindly when their communication link goes down.

Try to keep the FW setup from unloading the "nf_conntrack" module or 
otherwise fiddle with connection tracking. This should prevent any harm 
in the FW restart case.

In addaditon, if you expect any prolonged FW downtime to happen (for 
example: FW stop, explain situation to your boss, FW start), you may 
also like the usual "stateful accept" rule

  iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

to be present during the FW downtime.


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