Forward: I'm using Java 6u45, WebLogic 10.3.6, and Ubuntu Desktop 14.04 64-bit.
I just started as a student assistant at one of my state's IT offices. On my first day I was tasked with testing WebLogic on Ubuntu (Windows isn't cases sensitive, causing later issues because WebLogic is...). I started messing around with clustering, and now my setup is as follows:
1 Ubuntu machine
1 domain
6 servers: Admin server, wls1-4, and wlsmaster (wlsmaster was supposed to be what wls1 and wls2 reported to within the cluster because I set the cluster to be unicast, but that's a secondary question for now).
2 clusters: cluster1 and cluster2. wls1, wls2, and wlsmaster are on cluster1. wls3 and 4 are on cluster2.
Given my setup, do I even need to use node manager because I'm only using one physical machine? Secondary question; if I want to use unicast, how do I set the master? $state uses unicast for what few Weblogic servers we have, so I was told to check that out.
A few things:
No, you don't necessarily have to use a nodemanager, but it will make your life easier. When you log into the weblogic admin console and attempt to start one of your servers e.g. wls1-4, the Admin server will attempt to talk to the node manager to start the servers. Without the nodemanager you will have to start each server individually using the startManagedWebLogic.sh script and if you need to bring servers up and down often it will be very annoying.
With regards to Unicast it is pretty easy to set up (we just leave all the default values alone). Here is the pertinent info from the Oracle Docs:
"Each of the Managed Servers in a WebLogic Server cluster has a name. For unicast clusters, WebLogic Server reads these Managed Server names and then sorts them into an ordered list by alphanumeric name. The first 10 Managed Servers in the list (up to 10 Managed Servers) become the first unicast clustering group. The second set of 10 Managed Servers (if applicable) becomes the second group, and so on until all Managed Servers in the cluster are organized into groups of 10 Managed Servers or less. The first Managed Server for each group becomes the group leader for the other (up to) nine Managed Servers in the group."
So you will want to name your master servers in such a way that they are the first alphanumerically in the cluster. That said, for your use case I doubt you need those master servers as all. Just have 2 clusters, one with wls1-2 and one with wls3-4.
Related
I am using apache ignite with default configurations. I have two development server A and B where each server has the same code. I have 3 ignite nodes started on each server. 3 ignite nodes on A and 3 on B
I have created a ignite cache " ignite-bridg". Since on one server each node would create a cache and partition the data and these two servers are isolated so nothing will happen.
However I see that both the servers form a cluster and 6 nodes get connected. This is highly problematic for me. I think this is happening because both servers are accidently on same multicast group.
How to resolve this problem. I need to rectify it quickly
By default Ignite uses Multicast IP finder (TcpDiscoveryMulticastIpFinder) for nodes discovery process, in your case you should use Static IP finder (TcpDiscoveryVmIpFinder) instead. By using it you could specify different lists of IP addresses for each server and form two clusters instead of one.
Here is more information regarding Static IP Finder configuration:
https://www.gridgain.com/docs/latest/developers-guide/clustering/tcp-ip-discovery#static-ip-finder
I just investigate DC/OS, I find that DC/OS has three roles:master, slave, slave_public, I want to deploy a cluster which can host master, slave or slave_public roles on one host, but currently I can't do that.
I want to know that why can't put them on one host when designed. If I do that, could I get some suggestions?
I just have the idea. If I can't do, I'll quit using DCOS, I'll use mesos and marathon.
Is there someone has the idea with me? I look forward to the reply.
This is by design, and things are actually being worked on to re-enforce that an machine is installed with only one role because things break with more than one.
If you're trying to demo / experiment with DC/OS and you only have one machine, you can use Virtual Machines or Docker to partition that one machine into multiple machines / parts which you can install DC/OS on. dcos-vagrant and dcos-docker can help you there.
As far as installing though, the configuration for each of the three roles is incompatible with one another. The "master" role causes a whole bunch of pieces of software to be started / installed on a host (Mesos-DNS, Mesos master, marathon, exhibitor, zookeeper, 3dt, adminrouter, rexray, spartan, navstar among others) which listen on various ports. The "slave" role causes a machine to have a mesos-agent (mesos renamed mesos-slave to mesos-agent, hence the disconnect) configured and started on the agent. The mesos-agent is configured to control / most ports greater than 1024 to tasks which are launched by mesos frameworks on the agent. Several of those ports are used by services which are run on masters, resulting in odd conflicts and hard to fix bad behavior.
In the case of running the "slave" and "slave_public" on the same host, those two conflict more directly, because both of them cause mesos-agent to be run on the host, with slightly different configuration. Both the mesos-agent (the one configured with the "slave" role and the one with the "slave_public" role are configured to listen on port 5051. Only one of them can use it though, so you end up with one of the agents being non-functional.
DC/OS only supports running a node as either a master or an agent(slave). You are correct that Mesos does not have this limitation. But DC/OS is more than just a Mesos/Marathon. To enable all the additional features of DC/OS there are various components built around Mesos and Marathon. At times these components behave differently whether they are running on a master or an agent and at other times the components that exist on a master may or may not exist on an agent or vice versa. So running a master and an agent on the same node would lead to conflicts/issues.
If you are looking to run a small development setup before scaling the solution out to a bigger distributed system DC/OS Vagrant might be a good starting point.
Currently I have the following setup:
Hardware load balancer directing traffic to two physical servers each with 2 instances of weblogic running.
Works ok. I'd like to be able to shutdown one of the servers without dropping active sessions. Right now if I shutdown one of the physical servers any traffic that was going there gets bounced back to a login screen.
I'm looking for the simplest way of accomplishing this with the smallest performance hit.
Things I've considered so far:
1. See if I can somehow store the session information on the Load Balancer and through some Load Balancer magic have it notice a server is dead and try another one with the same session information (not sure this is possible)
2. Configure weblogic clustering. Not sure what the performance hit would be. Im guessing this is what I'll end up with, but still fishing for alternatives.
3. ?
What I currently have is an overly designed DR solution (which was the requirement), but I'd like to move it more in the direction of HA (for the flexibility)
edit Also is it worthwhile to create 2 clusters and replicate the sessions between them (I was thinking one cluster per site, sites are close enough). This would cover the event of one cluster failing.
You could try setting up a JDBC Session Storage pointing (of course) both instances to the same datasource without setting up a cluster, but I think the right approach would be setting up a Weblogic Cluster.
A nice thing about clustering Weblogic Servers is that - (from the link above, emphasis mine):
Sessions can be shared across clustered WebLogic Servers. Note that session persistence is no longer a requirement in a WebLogic Cluster. Instead, you can use in-memory replication of state. For more information, see Using WebLogic Server Clusters.
We've got a write up of this on our blog http://blog.c2b2.co.uk/2012/10/basic-clustering-with-weblogic-12c-and.html which provides step by step instructions on setting up web session failover in a cluster.
Clusters are not heavyweight assuming you don't store huge amounts of data in the cluster as it will be replicated.
LDAP Fault-tolerance configuration (e.g SunOne):
Does anyboby know how to configuration "Fault-tolerance" for LDAP, e.g SunOne LDAP.
I search via google without any userful result?
Thanks
Assuming, by "fault tolerance," "high availability (HA)" is being asked, I would say it can be achieved by redundancy. And, it would not be peculiar to SunOne or any directory server software from other vendors.
There are different ways to solve this. It depends on the business requirements and the affordability. One method that comes to mind is to have the LDAP software installed on an HA pair. This requires hardware and OS capabilities for fail-over and it requires two servers (in a world of virtualization, "server" can mean different things [physical box, frame, LPAR, etc.]; so, I'll just leave the interpretation to the reader). When one server fails, the other server takes over and assumes the primary role in the pair. This is the fault-tolerance part. In this approach, the machine/server with the secondary role is passive (i.e., it's not serving clients) until the primary goes down. You will need to implement LDAP data replication between two servers. They can be two LDAP masters in a P2P replication topology.
Another method is to have multiple LDAP servers (i.e., masters, replicas) and cluster them using a network dispatcher (ND) software/appliance/etc., which would distribute the incoming traffic to the individual servers (usually replicas) in the cluster. If you lose one replica in the cluster, ND will not send any traffic to that replica until it comes back. However, other replicas will still be receiving load and therefore serving to the incoming traffic. This is the fault-tolerance part in this method. The degree of the availability you want will also dictate what can be done in a clustered environment. You can have a single LDAP master (to which the organization's applications would make updates) and keep it out of the cluster, but pair with another server for fail-over (so you wouldn't lose availability for updates from the applications - this also gives you the freedom to do maintenance on the master without interrupting your applications [well, they need to be written to be able to write to more than one LDAP master if the primary one is not available]). You would have to have the secondary server to receive replication from the primary in any case. If the budget doesn't let you have more servers/replicas, then you can put the master server along with replicas in the cluster as well to help with the read traffic. Instead of an HA-pair in which one of the servers would be passive, you can have two masters configured in a P2P replication topology and have them both in the cluster to help with the traffic too. There are different ways to approach to this method depending on the level of redundancy wanted or that can be afforded.
We have a number of web-apps running on IIS 6 in a cluster of machines. One of those machines is also a state server for the cluster. We do not use sticky IP's.
When we need to take down the state server machine this requires the entire cluster to be offline for a few minutes while it's switched from one machine to another.
Is there a way to switch a state server from one machine to another with zero downtime?
You could use Velocity, which is a distributed caching technology from Microsoft. You would install the cache on two or more servers. Then you would configure your web app to store session data in the Velocity cache. If you needed to reboot one of your servers, the entire state for your cluster would still be available.
You could use the SQL server option to store state. I've used this in the past and it works well as long as the ASPState table it creates is in memory. I don't know how well it would scale as an on-disk table.
If SQL server is not an option for whatever reason, you could use your load balancer to create a virtual IP for your state server and point it at the new state server when you need to change. There'd be no downtime, but people who are on your site at the time would lose their session state. I don't know what you're using for load balancing, so I don't know how difficult this would be in your environment.