The OneConnect feature works with HTTP Keep-Alives to allow the BIG-IP system to minimize the number of server-side TCP connections by making existing connections available for reuse by other clients. "Hence, applying a OneConnect profile to a virtual server with only one pool member is considered a bad configuration since there will be only one TCP connection in the server-side of the connection."
I don't understand the statement "only one TCP connection" in server-side connection. Is that related to "one connection" per (external) client or for all external clients (what I can't believe)?
It sounds like "oneconnect" makes not sense with only one pool member because oneconnect hasn't not effect in this case. But for my understanding oneconnect should also reduce server-side connections with only one pool member ...right? If a connection is marked for reuse (create by first client), second external client can use that. Otherwise the second client will create a new server-side connection (if the first connection is still in use). After that there are two server-side connections (against the statemant "only one TCP connection").
@ndbs The amount of connections is completely dependent on the OneConnect profile settings so this answer could be different based on that and where your sources are coming from. Additionally, OneConnect has a side effect that it looks at every HTTP request and runs that through various HTTP related tasks such as iRules so it could be very usefull if in that iRule you had different destination pools for certain uri or host fields.