iRule Help for Web front end and Backend Database server traffic to failover at same time

What is the mechanism on the database server that makes it so web1 has to speak with db1 and web2 has to speak with db2? Typically you don't have a hard link between web and db servers because of the obvious downside such as yours. I'm not aware of how to do this with priority group activation but if you created 2 pools for web and 2 for db you could have the following logic.

*** Web irule ***
if pool-web1 active members <= 0 forward traffic to pool-web2 else forward to pool-web1

*** DB irule ***
if pool-db1 active members <= 0 and pool-web1 active member <=0 forward to pool-db2 else forward to pool-db1

Hi bob3,

you can achieve this without iRules but with a good combination of health check monitors and priority group activation.

1. Create two pools, lets call them pl_web and pl_sql. Add the web servers to pl_web and the db servers to pl_sql. Use priority group activation, to make sure all the traffic goes to the 01 server.
   Do not add a monitor to the pool.
2. Create four health check monitors, one for each server.
   You can do this by specifing the Alias Address in each monitor. This way the monitor will only check the server with the IP specified in the alias field.
3. Add the monitors to the pool members like this:
   Web server 01 will have the monitor for itself and DB server 01
   DB server 01 will have the monitor for itself and web server 01
   Web server 02 will have the monitor for itself and DB server 02
   DB server 02 will have the monitor for itself and web server 02
   Go to Local Traffic ›› Pools : Pool List ›› pl_web. Click on the Members tab. Click on the first member.
   Add member specific monitors as described above, two per server. Make sure Availability Requirement is All (default).
   Repeat this for all four servers in the two pools.

With this configuration the web server 01 will go down if either itself or the DB server 01 fails. With priority group activation you make sure all the goes only to either one pair or to the other. And priority group activation will also ensure that the failback works.

KR
Daniel