1. What is clustering? How do weblogic instances communicate
in a clustered environment!
2. In a cluster, if one of the servers has issues and is not
accessible, will the other servers know about it? and how??
Re: 1. What is clustering? How do weblogic instances communicate
in a clustered environment!
2. In a cluster, if one of the servers has issues and is not
accessible, will the other servers know about it? and how??
A WebLogic Server cluster consists of multiple WebLogic
Server server instances running simultaneously and working
together to provide increased scalability and reliability.
A cluster appears to clients to be a single WebLogic Server
instance. The server instances that constitute a cluster
can run on the same machine, or be located on different
machines. You can increase a cluster’s capacity by adding
additional server instances to the cluster on an existing
machine, or you can add machines to the cluster to host the
incremental server instances.
Re: 1. What is clustering? How do weblogic instances communicate
in a clustered environment!
2. In a cluster, if one of the servers has issues and is not
accessible, will the other servers know about it? and how??
1)A WLS clustr consists a group of server instances that
work together and look like a single instance to the
client.Cluster provides increased scalability, high
availability, load balancing, reliability etc.Through
multicaste adresses all the WLserver will communicate
through Heart Beat.For ever few sec the WLS instances will
release thir heart beats and if any of the server instances
does not release the heart beat then that server in
unavailable.And the stub also refreshes its list very
periodicaly so that it can know the available server
instances.
2)Yes, the other server will know through Heart Beats.
Re: 1. What is clustering? How do weblogic instances communicate
in a clustered environment!
2. In a cluster, if one of the servers has issues and is not
accessible, will the other servers know about it? and how??
1. cluster is group of WLS instances which are capable of
sharing loads (through load balancing) and providing high
availability for all deployments.
Weblogic instance uses the multicast address to
commmunicate with each other (to communicate their status
to other members of the cluster).
2. Yes, Server instances are aware of the accessibility of
the other members of the cluster (as each server instance
sends heartbeats on <multicast address>:<multicast port>)
and hence are failover capable.
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