[DRBD-user] RH Cluster Integration

drbd at bobich.net drbd at bobich.net
Mon Mar 10 13:00:27 CET 2008

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


Is there a way to integrate DRBD with RHC? I've found documentation on 
heartbeat integration, but nothing specific for RHCS.

In particular, if I have 2 nodes connected, and one of them disconnects 
briefly, DLM will lock up and wait for the nodes to reconnect or for one 
node to get fenced. DRBD will also disconnect. If, before fencing occurs, 
the network connection is re-established, GFS/DLM will re-connect, but 
DRBD will not. GFS will remain convinced that the file system is shared 
when the underlying DRBD volume is actually split-brained.

Is there a way to make DRBD force fencing of the other node on disconnect 
using the RHC hooks? Failing that, a direct fencing script hook would do.

I am currently using these SB resolutions:

after-sb-0pri   discard-younger-primary;
after-sb-1pri   discard-secondary;
after-sb-2pri   call-pri-lost-after-sb;

I can see in the docs that if it is decided that the current secondary is 
current, the primary gets panicked. But what happens of both nodes 
disconnect and decide to go into Primary/Unknown mode? Is there a hook 
that gets called when this is detected (if it is detected) that can be 
used to initiate fencing? This would be avoided if the nodes tried to 
re-sync after the connection is established, but they don't appear to do 
that for whatever reason. Am I missing an important setting somewhere?



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