Load Balancing WWW to SQL in seperate pools and VLANS

What is the most efficient and lowest latency configuration to LB a Webserver with SQL backend? Lets say for simplicity sake the LTM is configured with 3 VLAN's:

 

 

- External VLAN

 

- WWW VLAN

 

- SQL VLAN

 

 

The IP configuration is:

 

 

- External 10.10.0.x/24

 

- WWW 10.10.100.x/24

 

- SQL 10.10.200.x/24

 

 

The physical architecture is:

 

 

------------

 

-External -

 

------------

 

|

 

|

 

----------- ------------ --------------

 

- LTM -===Trunk===- Switch --------------- WWW -

 

----------- ------------ --------------

 

|

 

|

 

-----------

 

- SQL -

 

-----------

 

 

My goal is to LB the webservers and the SQL servers and have the VIP's that resolve via DNS reside on the External VLAN. https://www.mycompany.com resolves to 10.10.0.100 and the self IP for that VLAN is 10.10.0.10. The webservers have listening instances with IP's of 10.10.100.200, 10.10.100.201, 10.10.100.202 and SQL has instances of 10.10.200.200, 10.10.200.201 and 10.10.200.202 and a VIP of 10.10.200.100. I think I got everything...

 

 

Questions:

 

 

1. I have a pool of WWW servers and a pool of SQL servers. Whats the best way to LB the WWW connection to the SQL servers?

 

 

2. Is there a way to achieve this goal without SNATing?

 

 

3. In the past I have always recommended a direct connection to the SQL backend for lower latency and security. Is there any benefit to LBing the SQL servers in their own pool, with their own VIP?

 

 

4. Which type of persistence would you recommend?

 

 

5. What are the drawbacks?

 

 

6. What if I need uri-a to go to SQL server-a, b or c? Do you have a canned iRule?

 

 

7. Do you recommend a different architecture?

 

 

 

Thanks!!! Looking forward to your response. :)

 

 

RHally