Can you add a direct network link to existing cluster?

[CelticWebs]

I have a small cluster of just 2 devices, I will be adding a 3rd in the not too distant future.

One of the nodes has 10gb uplink to external, the other only has 1gb. This means that synching between the two is limited to 1GB of course. I've added a 10gb network card to the node with 1GB network link, I don't have another 10gb uplink port to connect to as the switch only has 2 10gb capable SFP ports, one is connected to the 10gb node and the other is on the uplink in the DC. What I'd like to do is link the two nodes together as an internal link using their available 10gb ports, is it possible to tell corosync to use this new link for node communications instead of using the old ones?

I'm assuming updating the corosync files with new IP addresses for the nodes would be enough but I'm not quite sure on the best way to go about setting it up, assuming it's possible at all of course.

What are your thoughts on this? Is it possible? If so, how would you go about it?

 

[cheiss]

Hi,

you are essentially describing a so-called meshed network setup.
We have some documentation on how to setup such a network. Albeit the guide is for three nodes and Ceph, it should be generic enough. As for the corosync setup, you can follow our guide on how to add redundant links to an existing cluster.

I have a small cluster of just 2 devices

You are hopefully currently running the cluster with external vote support or are aware of the consequences that result from a 2-node cluster. Just FYI.

 

[CelticWebs]

You are hopefully currently running the cluster with external vote support or are aware of the consequences that result from a 2-node cluster. Just FYI.

I'd never heard of external vote support! This is the first time I've seen this mentioned when anyone said they were only running 2 nodes. I'll take a look, thanks

 

[UdoB]

I will be adding a 3rd in the not too distant future.

Regarding the "Mesh"-approach mentioned by @cheiss : be aware that each and every node needs one NIC for every other member. For three nodes every node has two neighbors and needs two NICs. It does not scale well... think about adding a fourth node in a possible future...

Just wanted to mention this. Have fun!