This parameter forces SharePlex to use the defined hostname(IP) wherever it stays…
So, if the hostname can be resolved in the server, SharePlex will be fine.
Another thing is that: If there are multiple network interfaces in the system, normally, SharePlex will use just the "primary" network card to communicate to the target system unless the SP_SYS_HOST_NAME is set.
For this reason, if you want to use the other network interface instead of Primary network, you should set this parameter.
We can think of it as a global hostname.
For example,
Node1’s IP is 12, and Node2’s IP is 13. Global VIP is 15 and its hostname is PRINCE.
If we set SP_SYS_HOST_NAME=PRINCE,
On Node1, SharePlex is mapped with PRINCE, there is no issue to start SharePlex in Node1.
Does it make sense?
Although the Global VIP moved to Node2, as the Global VIP hostname can be resolved in the Node2 and
SharePlex is mapped with PRINCE, there is no issue to start SharePlex in Node2 as well.
This is how the parameter works.