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Prashanth Waugh
Esteemed Contributor




I have 4 node cluster, I am planning to take one node outside the cluster by using cmhaltnode command. There are three nodes in cluster. Now if am applying the cluster changes using cmapplyconf , so  will it be applied on the node which is outside the cluster. If not how to apply cluster changes later  on this node.




For success, attitude is equally as important as ability
Honored Contributor

Re: cmhaltnode

Using cmhaltnode does not halt the entire operating system, just the cluster functionality. If the OS is still running and the halted node is still reachable from the other servers, cmapplyconf will apply the configuration change to all 4 nodes.

In this case, having the 4th node rejoin the cluster is very simple: just run "cmapplyconf"


If the node is not reachable, cmapplyconf will reject the configuration attempt because of that.


(There are some cluster configuration changes that require the entire cluster to be halted to apply the new configuration, so having all the nodes running the cluster is not a requirement for cmapplyconf. The nodes will just need to be reachable.)



If you need to make other changes to the cluster configuration while the 4th node is unreachable (i.e. powered down or network disconnected), you must temporarily change your cluster to 3-node configuration before you can make any more changes.


To do that, you must comment out all references to the 4th node from the cluster configuration ASCII file and all the package configuration files, and then apply the updated cluster configuration and any updated package configurations in a single cmapplyconf step. Now you have a 3-node cluster and the 4th node is definitely thrown out.


Later, when you wish to bring the 4th node back, you can run "cmdeleteconf" on the 4th node with no arguments to clean up the old out-of-sync configuration from that node, then bring back to the cluster just like when adding a new cluster node.


Basically, uncomment the commented-out references to it in the cluster configuration ASCII file (modifying to match your earlier modifications done while in 3-node configuration if necessary), then use cmapplyconf to rejoin the node to the cluster, then update the package configurations in the same way if necessary to allow the packages to move to the "new" 4th node.