[ClusterLabs] Centreon HA Cluster - VIP issue

[Ken Gaillot]

Hi,

The scenario you describe is still a challenging one for HA.

A single cluster requires low latency and reliable communication. A
cluster within a single data center or spanning data centers on the
same campus can be reliable (and appears to be what Centreon has in
mind), but it sounds like you're looking for geographical redundancy.

A single cluster isn't appropriate for that. Instead, separate clusters
connected by booth would be preferable. Each cluster would have its own
nodes and fencing. Booth tickets would control which cluster could run
resources.

Whatever design you use, it is pointless to put a quorum tie-breaker at
one of the data centers. If that data center becomes unreachable, the
other one can't recover resources. The tie-breaker (qdevice for a
single cluster or a booth arbitrator for multiple clusters) can be very
lightweight, so it can run in a public cloud for example, if a third
site is not available.

The IP issue is separate. For that, you will need separate floating IPs
at each cluster, on that cluster's network. To fail over, you update
the DNS to point to the appropriate IP. That is a tricky problem
without a universal automated solution. Some people update the DNS
manually after being alerted of a failover. You could write a custom
resource agent to update the DNS automatically. Either way you'll need
low TTLs on the relevant records.

On Sun, 2023-09-03 at 11:59 +0000, Adil BOUAZZAOUI wrote:
> Hello,
>  
> My name is Adil, I’m working for Tman company, we are testing the
> Centreon HA cluster to monitor our infrastructure for 13 companies,
> for now we are using the 100 IT license to test the platform, once
> everything is working fine then we can purchase a license suitable
> for our case.
>  
> We're stuck at scenario 2: setting up Centreon HA Cluster with Master
> & Slave on a different datacenters.
> For scenario 1: setting up the Cluster with Master & Slave and VIP
> address on the same network (VLAN) it is working fine.
>  
> Scenario 1: Cluster on Same network (same DC) ==> works fine
> Master in DC 1 VLAN 1: 172.30.9.230 /24
> Slave in DC 1 VLAN 1: 172.30.9.231 /24
> VIP in DC 1 VLAN 1: 172.30.9.240/24
> Quorum in DC 1 LAN: 192.168.253.230/24
> Poller in DC 1 LAN: 192.168.253.231/24
>  
> Scenario 2: Cluster on different networks (2 separate DCs connected
> with VPN) ==> still not working
> Master in DC 1 VLAN 1: 172.30.9.230 /24
> Slave in DC 2 VLAN 2: 172.30.10.230 /24
> VIP: example 102.84.30.XXX. We used a public static IP from our
> internet service provider, we thought that using a IP from a site
> network won't work, if the site goes down then the VIP won't be
> reachable!
> Quorum: 192.168.253.230/24
> Poller: 192.168.253.231/24
>  
>  
> Our goal is to have Master & Slave nodes on different sites, so when
> Site A goes down, we keep monitoring with the slave.
> The problem is that we don't know how to set up the VIP address? Nor
> what kind of VIP address will work? or how can the VIP address work
> in this scenario? or is there anything else that can replace the VIP
> address to make things work.
> Also, can we use a backup poller? so if the poller 1 on Site A goes
> down, then the poller 2 on Site B can take the lead?
>  
> we looked everywhere (The watch, youtube, Reddit, Github...), and we
> still couldn't get a workaround!
>  
> the guide we used to deploy the 2 Nodes Cluster: 
> https://docs.centreon.com/docs/installation/installation-of-centreon-ha/overview/
>  
> attached the 2 DCs architecture example, and also most of the
> required screenshots/config.
>  
>  
> We appreciate your support.
> Thank you in advance.
>  
>  
>  
> Regards
> Adil Bouazzaoui
>  
>   	 Adil BOUAZZAOUI Ingénieur Infrastructures & Technologies 	
>  GSM         : +212 703 165 758 E-mail  : adil.bouazzaoui at tmandis.ma 
>  
>  
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-- 
Ken Gaillot <kgaillot at redhat.com>