Selective Priority Group Activation

My question:

I have a set-up in which a pool contains 8 members:

• 4 at priority level 1 and
• 4 at priority level 2

I want traffic to be directed to the primary members (priority level 2) until the point at which there is only 1 member remaining (judged dead by a health monitor). At this point I want traffic to be routed entirely to priority level 1 pool members and not at all to the last remaining level 2 member.

I looked at Priority Group Activation, but this seems to start supplementing priority level 2 members with members from the lower priority pool... rather than switching all traffic to the lower priority pool at a specified point.

I do not want to set the Priority Group Activation "Less than 1", which would leave me with only 1 server in priority group 2; would result in all traffic flowing through a single box.

Using priority group activation appears to mix traffic between separate priority groups - I want to use one or another... but switch to the lower priority entirely at a specific point.

Any help appreciated

Any help in posting would be appreciated.