I have an application running on two servers. There is a mariadb running on each one of them and a galera cluster that takes care of the replication.
When upgrading the app I need to stop the replication, so I wanted some guidelines on how I can start up the db outside the cluster for one of the servers and then what's the best way to reconnect it.
All ideas are appreciated
Thanks in advance
You can remove the node from the cluster by setting 'wsrep_cluster_address=gcomm://' in the config file of the node.Then restart the server,this time the node will be running outside the cluster,hence,no replication.Similarly,to reconnect change the wsrep_cluster_address to whatever it was earlier and restart the node.
Hope it helps.
Related
I have a 5 node Service Grid running on an Ignite 2.10.0 Cluster. Testing the upgrade, I stop one Server Node (SIGTERM) and wait for it it rejoin. It fails to stay connected to the cluster?
Each node is a primary micro service provider and a back for another (Cluster Singletons). The service that was running on the node that left the cluster is properly picked up by it's backup node. However, the server node can not stay connected to the cluster ever again!
Rejoin strategy:
Let systemd restart ignite.
The node rejoins, but then the new Server Node invokes it's shutdown-hook
Go back to 1
I have no idea why the rejoined node shuts itself down. As far as I can tell, the Coordinator did not kill this youngest Server Node. I am logging with DEBUG and IGNITE_QUEIT set to false; I still can't find anyting in the logs.
I tried increasing network timeouts, but the newly re-joined node still shuts down???
Any idea what is going on or where to look?
Thanks in advance.
Greg
Environment:
RHEL 7.9, Java 11
Ignite configuration:
persistence is set to false.
clientReconnectDisabled is set to true
I have two servers in a HA mode. I'd like to know if is it possible to deploy an application on the slave server? If yes, how to configure it in jgroups? I need to run a specific program that access the master database, but I would not like to run on master serve to avoid overhead on it.
JGroups itself does not know much about WildFly and the deployments, it only creates a communication channel between nodes. I don't know where you get the notion of master/slave, but JGroups always has single* node marked as coordinator. You can check the membership through Channel.getView().
However, you still need to deploy the app on both nodes and just make it inactive if this is not its target node.
*) If there's no split-brain partition, or similar rare/temporal issues
I have installed HDP Ambari with three nodes in VM, i restarted one of three nodes i.e., datanode2 after that, i lost heart beat from that node in Ambari. I restarted ambari-agent in all three nodes, then also not working. Kindly find me a solution.
Well the provided information is not sufficient, anyway i will try to tell you the normal approach I take to debug this.
First check if all the ambari-agents are running, use the command ambari-agent status.
Check the logs of both ambari-agent and ambari-server. Normally the logs are available at /var/log/ambari-agent and /var/log/ambari-server. Logs should tell you the exact reason for heartbeat lost.
Most common reasons for the agent failure would be Connection issues between the machines, version mismatch or corrupt database entry.
I think log files should help you.
I installed Datastax community version in an EC2 server and it worked fine. After that I tried to add one more server and I see two nodes in the Nodes menu but in the main dashboard I see the following error:
Error: Call to /Test_Cluster__No_AMI_Parameters/rc/dashboard_presets/ timed out.
One potential rootcause I can see is the name of the cluster? I specified something else in the cassandra.yaml but it looks like opscenter is still using the original name? Any help would be grealy appreciated.
It was because cluster name change wasn't made properly. I found it easier to change the cluster name before starting Cassandra cluster. On top of this, only one instance of opscentered needs to run in one single cluster. datastax-agent needs to be running in all nodes in the cluster but they need to point to the same opscenterd (change needs to be made at /var/lib/datastax-agent/conf/address.yaml)
This is in regard to a big data analytics engine put out by http://hamrtech.com
Does Zookeeper have to be on its own server with HAMR?
No it does not have to be part of the hamr cluster but every node within the cluster must have access to it.