Heartbeat is sort of deprecated and the new “industry standard” will be pacemaker and OpenAIS. They’re very different animals, so be careful to read their roles. Pacemaker is a ‘cluster resource manager’ — the part you asked about in your original question. It can use OpenAIS or Heartbeat as the network layer to manage a … Read more
Assuming your rabbitmq clients can tolerate a dropped connection, you can consider what’s described here. our cluster is behind a VIP. When we want to upgrade a cluster, we spin up an alternate cluster and switch the VIP over to the alternate cluster. Meanwhile, we have tooling that moves messages between clusters. When the ‘master’ … Read more
Draw a picture of your request/response cycle for the application and isolate the bottleneck. You are correct that a single proxy distributing load to many application servers will require the aggregate bandwidth of all application servers. The classical solution is RR DNS. Google, Yahoo and Amazon all use this technique with a short TTL. I … Read more
After doing some research, it looks like you can’t downgrade cluster functional levels, nor can you live migrate instances from 2016 to 2012 anyways. I would suggest using server 2016 instead of a 2012 to get this job done. You’d have to put a lot of work into using the wrong tool for the job … Read more
The minimum number is 1 server. If by “production” you mean “fault tolerant” then the minimum number is 3: you have a replica set containing 3 servers. The config servers also run on these servers. If you want to include “horizontal scaling” i.e. “web scale!” as well then the minimum number is 9: you have … Read more
This is a slightly older question but the problem presented here is based on a misconception on how and when failover in clusters, especially two-node clusters, works. The gist is: You can not do failover testing by disabling communication between the two nodes. Doing so will result in exactly what you are seeing, a split-brain … Read more
Take a look on Rundeck – http://rundeck.org/
What you’re talking about is called Single System Image (SSI). The most common variant of this scheme for Linux is implemented by MOSIX. While it does provide some advantages in terms of system management, in general processes cannot span across multiple nodes without using some form of MPI. Basically whether or not you use a … Read more
The first question I would ask is do you want this replicated to two servers or more then two servers? For two servers I would go with DRDB, for three or more I would go with gluster. If I/O latency is not a critical concern I would go with gluster. It is pretty easy to … Read more
The type of cluster that presents as a single operating system with lots of memory, multiple CPUs and can run whatever would normally run on the non-clustered version of that OS is called a Single System Image. This takes multiple cluster nodes and does just what you said, merges them into a single OS instance. … Read more