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jquinones82_469's avatar
jquinones82_469
Icon for Nimbostratus rankNimbostratus
Aug 25, 2009

Priority Group Activation

I have a question in regards to your post and was wondering if you could assist me?

 

I have a Pool with 4 members, each with their own priority activation value

 

server 1 has a value of 4

 

server 2 has a value of 3

 

server 3 has a value of 2

 

server 4 has a value of 1

 

When server 1 fails, it fails over all connections to server 2, when server 2 fails, it fails all connections to server 3, etc...

 

This works as expected.

 

My questions is:

 

If I'm on server 4 and a node comes up with a higher priority activation value, it stays on server 4 until I close the session. Is there a way to automatically demote the node once the primary one comes back up?

 

For ex, If I'm on server 4 (Priority activation value of 1) and server 1 comes up or one with a high value, how can I have it automatically move me to that server or a server with a higher priority activation value?

 

New non-persistent connections will fall back to the higher priority servers, but I want to move persistent non-active connections to a server with a higher priority. How can I force a pool member offline line via an IRule to do this?
application delivery
dev
devops
iRules
  • The_Bhattman's avatar
    The_Bhattman
    Icon for Nimbostratus rankNimbostratus
    Aug 25, 2009
    if I understand your question correctly, if server 1 or one with the higher priority value comes up when you are on 4 you can't move a current session to another node. What can be done if irule is you can force the traffic to high priority servers which will establish a new session - essentially breaking the current persistence record and establishing a new one.

     

     

     

    CB
  • Kevin_Stewart's avatar
    Kevin_Stewart
    Icon for Employee rankEmployee
    Aug 25, 2009
    If I can expand on Cmbhatt's comments, forcing the user to break their persistence to one server in favor of another will BREAK their application session. There are very few commercial web applications out there that don't rely in some way on a session to track a user's movement through the application. If the application stores everything in a cookie (including authentication information), then you might be okay. But if that cookie (or header) is a session ID (PHPSESSIONID, ASPSESSIONID, CFID, JSESSIONID, etc.) that points to an in-memory session object on the server, then you will break the application and interrupt the user's experience. You're probably better off leaving existing users on the server. Many environments, including the BigIP, do allow some session mirroring capability, but it is hardly ever an easy option.

     

     

     

    Kevin