The current cluster is a high availability cluster and the node alias are
`controller1`controller2`controller3`agent1`agent2`agent3`NODE1`NODE2`NODE3.
How can I efficiently update licenses on all nodes?
You can use pnodeRun() function to the updateLicense function on all data nodes in the cluster. Here is an example:
pnodeRun(updateLicense(), `controller1`controller2`controller3`aget1`agent2`agent3`NODE1`NODE`NODE3)
Related
What is the meaning of the configuration item "balance" in the TDengine's configuration file taos.cfg?
Can TDengine balance data replicas in the cluster automatically？
Can TDengine balance leader membership in the cluster automatically？such as leader membership transfer in Raft?
"balance" is a parameter in configuration file which determine whether TDengine cluster should automatically start load balance when meet three situation:
When a new data node is added to the cluster, the system will automatically trigger load balancing, and the data on some nodes will be automatically migrated to the new data node without any manual intervention.
When a data node is removed from the cluster, the system will automatically migrate the data on the data node to other data nodes without any manual intervention.
If a data node is overheated (too large amount of data), the system will automatically load balance and migrate some vnodes of the data node to other nodes.
Is there any way I can insert data to only one node or shard of Solrv5.x and get it replicated to all the other nodes linked to it via zookeeper.
Thanks,
Ravi
This is what Solr does by default when running in SolrCloud mode (which is when it's using Zookeeper).
As long as you index to one of the nodes, the nodes will figure out where (which server has the collection) the document should go and which other servers it should be replicated to.
You set these settings when creating or changing a collection through the replicationFactor setting.
I have a question about failover clustering. If I set up failover clustering with 4 nodes and each node has a different instance of SQL Server running on it, will I need four separate licenses?
Yes you need to have separate licensing
We are new to Vertica and found it relatively surprising that only one database at a time can be UP/active. In our research work we need to access multiple databases at a time, so I'd like to know how other Vertica users manage this limitation. The only approaches I've thought of so far are a) taking turns (start and stop databases as needed), or b) (mis-)using schemas to group tables into logical databases. Thanks for your help!
You can have multiple databases. Each database would need dedicated nodes. With a 6 node cluster:
DB1 on node1, node2, node3
DB2 on node4, node5, node6
In order to maintain high availability, each database would require at least 3 nodes for a K-Safety level of 1. If the databases loses a node with K-level 1, the database will run normally.
The way Vertica is designed is intended for a single database instance. Vertica falls under the MPP (Massively Parallel Processing) category. Multiple databases would be competing for resources on a cluster. The parallel design enables the distribution of storage and workload across the nodes. The best design is to logically create your schemas like you would databases.
You can run more then one Vertica database even on the same node !! Yo just need to alter the port number where the database run on !!
But like #FreshPrinceOfSO said Vertica is quite hungry for resources (Memory in special). So is recomended to keep your Cluster with one database running on it!!!
I prefer to create a new cluster insted of mixing up the schemas !! Or if you choose to create schemas to behave like database repos you need to have a good knowladge of your resource management tasks!
I have a question for the DBA's out there: If I scale from a single web/DB server setup to two web/two DB server setup with a load balancer in front of the web servers to route incoming queries evenly... how do solutions like MySQL Cluster work so that a change made to one DB server is immediately known to the other (otherwise, users routed to the other DB server won't see the data or will outdated data), or at least so that the other web server is made aware of the fact that it's reading "dirty data" and it should try again in X seconds so as to get up-to-date data?
Thank you.
TWO ways of doing this.
Active/Active or Active/Passive.
Active/Passive is most prevalent
The data is kept in sync on the passive node.
The cluster is useful configuration in as much as the active node goes down the passive is immediately switched hence no downtime.
The clustering continuously synchronises the 2 nodes in the cluster.
I work with SQL server but I think the basic premise of clustering is the same for mySQL - that is no (or no noticeable) downtime on hardware failure.
EDIT: Additionally the clustering software handles the synchronisation. You don't need to worry. You view the cluster nodes as a virtual directory, which behaves like one server in windows.
here is document explaining this
http://www.sql-server-performance.com/articles/clustering/clustering_intro_p1.aspx
In Windows server clustering (to be distinguished from High Performance Clustering), there is a shared external storage array. The active node takes ownership/control of the storage, and when that node fails, the storage 'fails over' to the previously passive node (which is now the active node). There are also different schemes that allow for independent storage at each node, vs. shared storage. However, these require the application to have enough intelligence to know that it is clustered, and keep the two storage sets in sync.
Clustering is also where a number of nodes handle the workload, this is sometimes called active/active clusters i.e. all the nodes share the workload and are active. This is normally handled by specialist software like Oracle RAC (RAC#Wikipedia) for the Oracle RDBMS database. RAC allows Oracle to scale to very large workloads.