I would like to have a high-availability/redundant installation of Zookeeper running in my production environment. The problem is that I only have 2 physical frames available, so that rules out configuring a Zookeeper cluster/ensemble since I'd only have redundancy if the frame with the minority of servers goes down. What is the best practice in this situation? Is it possible to have a separate standalone install running on each frame connected to the same set of SOLR nodes or to use one server as primary and one as backup?
Zookeeper requires 3 nodes. In your scenario if you cannot get another machine you can setup multiple zookeeper nodes on the same machine in different directories using different ports.
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We have 2 app/web servers running HA application, we need to setup redis with high availability/replication to support our app.
Considering the minimum sentinel setup requirement of 3 nodes.
We are planning to prepare the first app serve with redis master and 1 sentinel, the second app server will have the redis slave and 1 sentinel, we plan to add one additional server to hold the third sentinel node to achieve the 2 quorum sentinel setup.
Is this a valid setup ? what could be the risks ?
Thanks ,,,
Well it looks its not recommended to put the redis nodes on the app servers (where it is recommended to put the sentinel nodes there).
We ended with a setup for KeyDB (a fork from Redis) which claimed to be faster and support high availability/replication (and much more) to create two nodes within the app servers.
Of course We had to modify little in the client side to support some advance Lua scripts (There is some binary serialized data not getting replicated to the other node).
But after some effort, it worked ! as expected.
Hope this helps ...
I tried to create a cluster in Apache Geode by providing the hostname and ip address of the remote system in the gemfire.properties file. Somehow, I am not able to create a cluster.
Can anybody please help with steps to create a cluster (including multi-site).
Thank you
It's not clear from the description if you just want to create a simple GemFire cluster or multiple clusters connected through the Geode WAN replication mechanism...
That said, to start a local Geode cluster you can go trough Apache Geode in 15 Minutes or Less, it's a quick introduction that shows you how to use gfsh to start a locator and some servers, create a region, monitor the system using PULSE, etc.
To setup WAN replication, on the other hand, you can go through Configuring a Multi-site (WAN) System, the most important thing to note about this configuration is that your locators need to know about the locators on the remote system, so you need to make sure that the property remote-locators is correctly configured. Once the locators can talk to each other over the WAN, they will share the connection information with the local servers and these, in turn, will be able to communicate with the servers on the remote clusters.
Hope this helps.
Cheers.
I am setting up a cluster of servers using vagrant and playing with Redis sentinel and HAProxy for Postgresql db connection (with pgpool). I was curious if it make sense to put haproxy and redis sentinel on each of my web server nodes and have them connect directly to those. The thought is that it can create a distributed connection to the DB and redis and reduce the single point of failure to having a single haproxy that they connect to and then split to different db nodes. I can also keep the database connect (via haproxy) and redis (via sentinel) encapsulated to the localhost. Does this make sense?
It only makes sense if you're trying to save up on resources/costs.
Please note that redis sentinel must have a finite list of sentinel instances, which doesn't fit the scenario of placing one per machine, as your maching count would probably scale/change.
Otherwise , it's always makes the most sense to put different infrastructure components ( especially those with clustering/HA nature, such as redis ) on different machines.
By mixing them all together, you usually end up with applications getting in the way of each other and stealing CPU from each-other once the load increases. You also risk designing your applications/scripts/flows to be location aware (i.e assume external resources are always local ) which is also not a really good practice.
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.
I want to know if it is possible to run 2 versions (5.5 and 5.10) of ActiveMQ on the same machine. I simply assume that all I need to do reconfigure the ports on one of them to something different to the other.
The reason for this is that we are using Informatica B2B which uses ActiveMQ # 5.5 with a 3rd party (Fuse) addition for its internal messaging. We would also like to run a separate JMS server on the same machine for various reasons using 5.10 or 5.11.
I have found lots of examples of creating multiple instances, but they apply to using the same installation.
If it is that simple (as just changing the ports), can they also share the same JVM or not?
You can run multiple instances on the same machine by changing the ActiveMQ configuration. You should assign each Broker a unique name and configure the transport connector to listen on different ports. You also want to ensure that they are configure with different data directory instances and so on.
You cannot run two in the same JVN however.