If you are looking for a cluster, but you have a low budget, there is another cluster schema you can have. It is what I call all the eggs in the same nest. This approach is not load-balanced and is far from a high-availability one. It is more a fault tolerance one, which means you still have some downtime but you can recover very easily.
So, just to be clear. This approach I will write about is not load-balanced, nor high-availability.
A Cluster Overview
A fault tolerance cluster needs a minimum of two servers. Each server is totally a stand-alone deployment.
The elements are:
- an active PBX (PBX 1) that has all the elements within. It has its public IP
- a backup PBX (PBX 2) that is a mirror of the active one. Some scripts sync the databases and the filesystems.
Pro's, Con's and Side Effects of a Fault Tolerance Cluster
So, this scheme is more a set of a stand-alone server than a cluster, however, the way it works it can be still considered a cluster. First I will talk about the pros:
- Cheap to deploy. The load-balanced or high-availability clusters need at least five servers to work. In this case, the minimum is two.
- It can be seen as a stand-alone deployment, so all the functionalities that FusionPBX has will work out of the box.
Some Cons:
- All the load hits a single server, so you should have enough muscle to support it.
- When the active PBX fails, you will be down until you change your DNS entries and you change your carrier's DID's IPs. If your DNS software and your carrier allow it, you may deploy a Nagios system that does the change for you.
So far, I have not found any side effects.
Fault Tolerance in the Cluster
As I have already said, This is more of a mirror system, one server will sync for periods against the other. If an event happens, the backup PBX will only lose some minutes of data, usually some voicemails and CDR records.
When you change the DNS records and your carrier's configuration, the new active server will start working.
Do not forget this is a one-way sync when you recover the PBX 1, you must return it as the more accurate information will be there.
How do I get a Cluster like this?
Easy, just send me a text on any of my social media accounts. I am sure we will get into an agreement and you will enjoy a brand new PBX Cluster.
Good luck!
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