How to configure mulitple webengines on APP servers behind an F5 Load Balancer in an Advanced Availability Environment

Products

• SUPPORT AUTOMATION- SERVER
• CA Service Desk Manager - Unified Self Service
• CA Service Desk Manager
• CA Service Management - Asset Portfolio Management
• CA Service Management - Service Desk Manager

Issue/Introduction

Typically, with an Advanced Availability architecture, its assumed that you would only have one webengine/domsrvr pair on each APP server.  However, in some environments, you may want to have more than one webengine/domsrvr pair on each of your APP servers to help further distribute the load without having to configure additional hardware or virtual machines.

Environment

CA Service Desk Manager 17.X.

Resolution

F5 load balancers can only distribute the load across servers, but not across webengines.  The only way to distribute a load across webengines is to use a web director within SDM itself.  Typically in an advanced availability environment, if you wanted to use more than one webengine/domsrvr pair on your app servers behind an F5, you would have the F5 distributed the load across servers, and then have a web director on each APP server to distribute that load across the webengines on that specific server.  To do this, you would need to configure the system as follows.

For Example, lets say you have the following setup:

- Background (BG)

- Standy (SB)

- 3-APP Servers (APP1, APP2 and APP3)

- F5 load balancer dividing the load among APP1, APP2 and APP3

- Currently:  one domsrvr/webengine pair on each APP server

- Goal: 4-domsrvr/webengine pairs on each APP server

Here is what you would need to do:

Go into the administration tab > system > configurations, and edit the configuration that you are using by doing the following on each APP server:

1. Create a Web Director

2. Edit the existing webengine (the original one) and set it to use the new web director on that specific server

3. Add 2 more Object Managers

4. Add 2 more Web Engines, setting each one to use its own appropriate domsrvr on that specific server, and setting each to use the Web Director you created in step-1

5. Save the configuration

6. Run pdm_configure on the BG (you will need to fail over to the SB first), SB (you will need to fail back to the original BG first), APP1, APP2 and APP3 servers in that order.

7. Point the F5 Load Balancer to distribute the load betweeen each of the 3 Web Directors on the APP servers - then the Web Directors will divvy up the load between the webengines on each APP server.

The configuration will look like this visually:

APP1:

WebDirector1

Domsrvr1

Domsrvr2

Domsrvr3

Webengine1 (Behind WebDirector1) (Set to use Domsrvr1)

Webengine2 (Behind WebDirector2) (Set to use Domsrvr2)

Webengine3 (Behind WebDirector2) (Set to use Domsrvr3)

APP2:

WebDirector1

Domsrvr1

Domsrvr2

Domsrvr3

Webengine1 (Behind WebDirector1) (Set to use Domsrvr1)

Webengine2 (Behind WebDirector2) (Set to use Domsrvr2)

Webengine3 (Behind WebDirector2) (Set to use Domsrvr3)

APP3:

WebDirector1

Domsrvr1

Domsrvr2

Domsrvr3

Webengine1 (Behind WebDirector1) (Set to use Domsrvr1)

Webengine2 (Behind WebDirector2) (Set to use Domsrvr2)

Webengine3 (Behind WebDirector2) (Set to use Domsrvr3)

F5 Load Balancer Flow looks like this:

-> APP1 ->WebDirector

->Webengine1

->Webengine2

->Webengine2

-> APP2 ->WebDirector

->Webengine1

->Webengine2

->Webengine2

-> APP3 ->WebDirector

->Webengine1

->Webengine2

->Webengine2

Additional Information

The information in this article has been included in our product documentation.

You can find further details here:

How to Configure Multiple CA SDM Web Engines on Application Servers?