F5 load balancing SMTP to 2 groups of servers

Hi Larry G,

 

 

If you go with the scenario that you have given you could suffer some adverse affects (depending on your traffic load and your server abilities).

 

 

If you have four servers in each group.

 

1 fails - traffic is redistributed to the remaining 3.

 

2 fail - traffic is redistributed to the remaining 2.

 

3 fail - traffic traffic goes the the remaining server and possibly overload the server and/or cause the responsiveness to degrade (again, depending on your traffic load).

 

 

I would suggest putting all eight servers in a single pool and using Priority Activation Groups with a set of requirements that can be easily adjusted to fit your needs.

 

 

Example:

 

Server 1 - Group 2

 

Server 2 - Group 2

 

Server 3 - Group 2

 

Server 4 - Group 2

 

Server 5 - Group 1

 

Server 6 - Group 1

 

Server 7 - Group 1

 

Server 8 - Group 1

 

 

NOTE: Group Number of the highest number is active, so set your "Primary" Servers in the highest group number.

 

 

Set Priority Activation Groups to less than 4. This will keep 4 servers active at all times.

 

 

If a server in Group 2 (Active Server Set) fails, a single server from Group 1 would be made active to keep the load distribution equal (no traffic spikes or performance degradation).

 

If two servers in Group 2 fail, two servers are activated in Group 1 and so on. When the servers in Group 2 are recovered, the traffic going to the server(s) in Group 1 will "finish up" the connections that they have and all new traffic would go back to normal. All automagically.

 

 

Just a idea to try. Hope this helps.