What is the best practice for the sync interface when connecting 2 cluster members using ClusterXL?
We have always connected the cluster members together using the sync interface between them. Just curious if that is according to best practice vs. connecting the members directly to a switch for sync.
And is it a common/best practice to bond sync interfaces as well? So dedicated two interfaces in a bond used for sync only.
I would say that bonding the sync interface is a very good idea.
Having 2 sync interfaces is not supported.
In my experience the preference was always a direct connection vs using a switch in between cluster members for sync. The reason behind this is if the switch experiences a failure it can cause the cluster to become unstable. A direct connection just removes a potential failure point/latency point. If the firewalls are not physically close enough to do a direct connection then using a switch is fine but my recommendation is always direct.
Bonding the sync interface is the correct way to do it as 2 sync interfaces (while technically supported) will cause issues. However, IMO I wouldn't bother bonding the Sync interface unless:
1) You find that you are over-running your sync interface with traffic. In most deployments this won't be the case, you need to be moving a lot of data or have some other special circumstances.
2) If you need a little extra redundancy. If you find you want to account for a single port failure in your cluster design then go ahead and bond but in my view you're not gaining a whole lot of redundancy. Just my .02
In our environment, we have 2 nodes 500 km away, so using direct connection is not possible.
Using 10G link is also recommended, preffered as 2x 10G bond interface.
Increased of RX/TX ring size is also good to have.
From my experience I can say it depends if is a physical cluster or virtual.
If it's physical the sync interface should be in a dedicated vlan and you should keep attention on CCP traffic. Some switches can cause problems with multicast traffic so you have to switch to CCP in broadcast.
In pre R80.10 you have to specify the cluster ID (or MAC magic or fwha_mac_magic) on both members (default value 1) and it must not be in conflict with other cluster on the network.
In a virtual environment (vmware) you have to check the security settings of the portgroups where the vNICs are connected on.
Further info can be found on this sk Connecting multiple clusters to the same network segment (same VLAN, same switch) or How to set ClusterXL Control Protocol (CCP) in Broadcast / Multicast mode in ClusterXL