F5 to load balance MS Sql Servers

Great thread, thought I'd jump in with a few comments.

 

 

First of all, definitely use the built in SQL monitor: works great, fully supported, checkbox config.

 

 

chenna said: Create a VIP that will listen on 1433 (SQL Server Port) and will point at a pool with 2 servers of which at any given point only one will be active. The pool members may be running SQL on a different port, like 1437 or something (I hope it works, I never tried this but not sure if the VIP and the Pool Member service should be on the same port..sounds like I am missing basics here..). just to clarify, yes, the pool members may run on different ports than the VS, and ports are automatically translated by default.

 

 

jr6311 said: I would rarely allow any software to have programmatic control over the settings on a production load balancer(s)...you're looking for trouble...

 

and citizen_elah said: A well designed integration not only increases the flexibility and power of the solution, but it also cuts the manpower required to manage the tedium of something much better controlled by a process. I have to agree with citizen_elah on this one. A simple iControl script triggered at the end of the data load that updates the pool on LTM to use the new DB pool member may be the best solution in this case, especially given the request for a fast changeover.

 

 

jr6311 also said: If your device is polling the DB (this table entry) and you want to either manually control what machine is used or there is a real machine failure, given your proposed solution won't you introduce your own issues if the DB table entry the F5 is polling for keeps sending it back to an undesireable server? Don't you now have to worry about load balancing the database table entry the F5 keeps polling for (what if it's not available)? If you do go the DB row route to use a monitor to set the status, these are is valid concerns, as is contention for the same login or same row concurrently by monitors originating from both members of the redundant pair. You would want to set a different value for that row when the DB is supposed to be UP, and only that server would be available for load balancing. That way a non-responsive server would never be chosen.

 

 

You're problem seems to be not one of load balancing, but of making available and controlling successful data loads. which is why the iControl solution is likely the most optimal for this requirement -- monitor timing is non-deterministic and not coordinated, and the chance of neither or both servers becoming available for the period equal to the monitor interval.

 

 

HTH

 

/deb