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Full Discussion: HACMP
Operating Systems AIX HACMP Post 302684885 by bakunin on Friday 10th of August 2012 08:57:09 AM
Old 08-10-2012
Quote:
Originally Posted by allwin
Recent network change in our environment took more then 25 seconds. It is caused issue in cluster.
OK, but: how often do you change the network in your environment? If this was a one-time occasion it is probably best to leave it as it is. Like zaxxon said already (words to this effect): if it isn't broken, then don't fix it.


Quote:
Originally Posted by allwin
Secondary server took leadership since it is not get any response from primary.
It is good practice to have at least one non-IP connection (i.e. disk heartbeat or even the old-style serial connection) to avoid this. But even if it happens: this is what HACMP is expected to do. If you really have a need to change this behavior this begs the question if HACMP/PowerHA is the right tool for your needs.

Quote:
Originally Posted by allwin
But actually primary was up and running. After network established it is able to get response but already some of resources moved to secondary.

So primary is gone in to graceful shutdown.
This is also to be expected. You don't want to get a "split-brain condition", that is: two hosts both believing they are (or should be) primary. You simply power on your once-primary host, start the cluster services, do an "extended cluster verification" (if you are really paranoid, which is a good trait for a systems administrator) and after successfully verfying the cluster do a resource-group move. Then you have the status quo ante again.

Btw., according to this (rather ancient) HACMP 4.4 document the trip interval is for configuring the DMS (Dead-Man-Switch). If a cluster node doesn't give answer for this amount of time (in seconds) the other node considers it to be dead and not only takes over the resources but also will initiate a shutdown if the node comes back.

Keeping this in mind there can't be any sensible "default" with which to stick- You will have to tune this to your needs. It will always be a trade-off between security - if a node becomes unresponsive you want to take it over as fast as possible - and serviceability - you don't want unnecessary takeovers. What your most sensible trade-off-value should be can't be determined without extensive knowledge of your sites necessities and the intricacies of your environment.

You're officially YOYO (you're on your own).

I hope this helps.

bakunin
 

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LEARN ABOUT HPUX

cmruncl

cmruncl(1m)															       cmruncl(1m)

NAME

       cmruncl - run a high availability cluster

SYNOPSIS

       cmruncl [-f] [-v] [-n node_name...]  [-t | -w none]

DESCRIPTION

       cmruncl causes all nodes in a configured cluster or all nodes specified to start their cluster daemons and form a new cluster.

       To  start  a  cluster,  a user must either be superuser(UID=0), or have an access policy of FULL_ADMIN allowed in the cluster configuration
       file. See access policy in cmquerycl(1m).

       This command should only be run when the cluster is not active on any of the configured nodes.  This command verifies the network  configu-
       ration  before  causing	the nodes to start their cluster daemons.  If a cluster is already running on a subset of the nodes, the cmrunnode
       command should be used to start the remaining nodes and force them to join the existing cluster.

       If node_name is not specified, the cluster daemons will be started on all the nodes in the cluster.  All  nodes	in  the  cluster  must	be
       available for the cluster to start unless a subset of nodes is specified.

   Options
       cmruncl supports the following options:

	      -f	Force cluster startup without warning message and continuation prompt that are printed with the -n option.

	      -v	Verbose output will be displayed.

	      -t	Test  only.  Provide  an assessment of the package placement without affecting the current state of the nodes or packages.
			The -w option is not required with the -t option as -t does not validate network connectivity, but assumes  that  all  the
			nodes can meet any external dependencies such as EMS resources, package subnets, and storage.

	      -n  node_name...
			Start the cluster daemon on the specified subset of node(s).

	      -w none	By default network probing is performed to check that the network connectivity is the same as when the cluster was config-
			ured. Any anomalies are reported before the cluster daemons are started. The -w none option  disables  this  probing.  The
			option should only be used if this network configuration is known to be correct from a recent check.

       RETURN VALUE
	      cmruncl returns the following value:

	       0   Successful completion.
	       1   Command failed.

EXAMPLES

       Run the cluster daemon:

	      cmruncl

       Run the cluster daemons on node1 and node2:

	      cmruncl -n node1 -n node2

AUTHOR

       cmruncl was developed by HP.

SEE ALSO

       cmquerycl(1m), cmhaltcl(1m), cmhaltnode(1m), cmrunnode(1m), cmviewcl(1m), cmeval(1m).

						      Requires Optional Serviceguard Software					       cmruncl(1m)
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