Disabled Vs Forced Offline

There's essentially three states that a pool member can be in. It can either be not servicing any connections, it could be actively servicing connections, and it can have persistent but possibly not currently connected connections. This last one simply means that there's a persistence table entry recorded for this pool member to some client.

When you disable a pool member, you allow it to continue to service already established connections and anything that's tied to it in the persistence table.

When you force a pool member offline, you're only allowing it to service already established connections. Both options will bleed off connections from the pool member, but the latter will generally do it more quickly.