Changing IP subnet for cluster/corosync

[Jon morby]

Is there a recommended way to change the subnet which CoroSync/Proxmox uses for it's "primary" interface, without breaking the cluster or experiencing excessive downtime?


For technical/design reasons, I need (want) to move the corosync traffic to a a different vlan and renumber the admin interfaces from a public network to a private / non routed network for security and to split the multicast traffic away from a shared customer network

 

[Alwin]

Check out the section "Separate After Cluster Creation", it is also a good option to use a second ring, as explained in the docs.
https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_cluster_network

 

[Jon morby]

Perfect, thanks - this is just what I needed

 

[kyriazis]

In the section "Separate After Cluster Creation", since there is only a single ring0_addr, does it mean that there is a single network interface? Don't we also need to change the IP address of each node, on top of modifying corosync.conf?

Thanks!

 

[Alwin]

In the section "Separate After Cluster Creation", since there is only a single ring0_addr, does it mean that there is a single network interface? Don't we also need to change the IP address of each node, on top of modifying corosync.conf?

When the entry was deleted from corosync.conf, then it is just another node in the same subnet.

 

[kyriazis]

When the entry was deleted from corosync.conf, then it is just another node in the same subnet.

Thanks,

but if there is a single subnet (network interface) then we have to change the system IP address at the same time as corosync.conf? On all nodes?

 

[Alwin]

but if there is a single subnet (network interface) then we have to change the system IP address at the same time as corosync.conf? On all nodes?

Well, did you read a little further in the documentation?
https://pve.proxmox.com/pve-docs/pve-admin-guide.html#pvecm_redundancy

 

[kyriazis]

Well, did you read a little further in the documentation?
https://pve.proxmox.com/pve-docs/pve-admin-guide.html#pvecm_redundancy

Yes, I did. Everything points to needing a second network interface, though. What is the process, however, of changing subnet (and mask) with a single network interface?

Thanks!

 

[Alwin]

Yes, I did. Everything points to needing a second network interface, though. What is the process, however, of changing subnet (and mask) with a single network interface?

Best use a second ring then you can switch it more easily. It is also recommend for redundancy. Otherwise you will need to restart all corosync instances to get quorum on the new subnet. Else change IPs in corosync.conf and restart corosync. HA should be disabled.