Load Balancing DB backend

1. The best way to load balance will probably depend on your actual configurations... Assuming that your client isn't pool aware (i.e. Not something like a RAC aware client) and you need a VS for it, make the VS as simple as possible. If you LB at the TCP level and do no L7 inspection etc, you should be able to run in accelerated mode (Using the ASIC in older hardware, or the FPGA in newer hardware)

 

 

2. Yes. If the SQL servers and the WWW servers use the F5 as a gateway back to the 'client'. (You can either set that with a default gateway, OR policy routing).

 

 

3. Control... If you have >1 SQL backend, it's easier on the client to let the F5 do the load balancing. You can do things like dispatching to the fastest SQL server, dedicate one to lower SLA/response time clients etc.

 

 

4. For the SQL. By IP address is easy. For the WWW traffic, I always recommend session cookies. However you could also implement something a bit more complex with iRUles if you really want.

 

 

5. The more you do at the F5, the more you need someone with F5 experience to diagnose problems. Generally however it's easier to perform a lot of diagnostics AT the F5 when it's present (That may be a consequence of having people who understand a lot of different things though as well).

 

 

6. Nope... But you could write one...

 

 

7. Yep. Where's your firewall?

 

Generally I'd recommend external---firewall---F5---backendservers. The 'backendservers' can be multiple VLAN's and you can force the direct (i.e. non-loadbalanced) traffic BETWEEN vlans via the firewall if required. (Or even something more complex where SOME traffic can go direct. All by using network VS's, or iRules).

 

 

 

Remember these are general suggestions... YMMV.