[Linux-cluster] Re: setting the heartbeat interval

[Patrick Caulfield]

Jonathan E Brassow wrote:
> Looking at the cman_tool man page, I don't see a way to change the
> heartbeat interval.  Dave, is there a way to change this while cman is
> part of a cluster?
> 
> To change the in memory version number or expected votes for cman, you
> would:
> 
> 1) change cluster.xml file
> 2) ccs_tool update <new xml file>
> 3) cman_tool version -r <new #> ; cman_tool expected -e <new expected #>
> 
> If cman_tool can change the heartbeat interval without restarting the
> cluster (or cman on each machine), it would look very much like step
> #3.  This can not be done through the GUI, because the GUI only changes
> the in memory version number.

A reply for the list:

The heartbeat & detection intervals for cman can be set by writing values into
/proc/cluster/conf/cman/hello_timer & /proc/cluster/conf/cman/deadnode_timer

These values are in seconds and take effect immediately (-ish, ie the new hello
timer will take effect after the last hello timer has expired). Because these
really need to be the same on all nodes I don't recommend changing them
on-the-fly though - they should be set between loading the module and running
cman_tool join.

There is also /proc/cluster/conf/cman/max_retries which some may like to
increase if they are seeing "No response to messages" reasons for a node being
kicked out of the cluster - you can change this any time you like with no ill
effects.

The version of cman_tool on the STABLE tag of CVS has code that will read these
values from CCS when "cman_tool join" is run. I think this should be in a future
RHEL4 Update.


-- 

patrick