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Load Balancing of J2EE Application

Former Member
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57

Hello,

I have a J2EE Application that we are planning to port to SAP and run on SAP CE 7.1 EHP1 and SAP CE 7.2

I currently have 2 Physical App Servers in our production and 1 Physical Database Server(Oracle).

I would like to understand from the experts here as to how the Load Balancing happens in SAP Environment.

As per my reading till now I have two options:

1. Seperately Install SAP CE on both App Servers. Deploy the application on both of these servers and use the same Database String to connect to Database from both instances. The problem I see is double maintenance of App Server. Can this also lead to some database issues. Advantage is that if one App Server is down, second can still run

2. As per SAP documents, Install a Primary App Server on one physical box. Install Additional App Server on second box. Deploy Application on both instances. The advnatage I see is that maintenance is less. But problem might be if Primary goes down, secondary will also go down.

So I would like to know from expers what is the typical model that is used and why. Thanks for your help

Regards,

S Tripathi

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Answers (2)

Answers (2)

sunny_pahuja2
Active Contributor
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Hi,

First of all, you should define why you need app server ? Do you need it for load balancing or High availability ? Concept of both the scenarios are different.

1) If you need it for load balancing then you can install web-dispatcher and access portal through it. It will distribute load on app server as well.

2) If you need it for HA then you have to do the installation as per HA document because as per SAP ASCS instance is SPOF. Central Instance and Dialog Instance are not SPOF. So, in this case if your CI goes down then DI will work. Without ASCS if CI does down then Dialog instance will also not work.

Thanks

Sunny

Former Member
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Hello Mr. Tripathi ,

Option 2 is the more typical way to increase capacity. Of course you can also increase capacity by simply adding additional server nodes to a single instance. if you are trying avoid downtime due to loss of one of the application servers, option 2 will still work. Just because the primary application server goes down does not mean the secondary will become unavailalbe. There are some cases where the secondary server could be interrupted, such as if the jms provider was on the primary instance, but there is an automatic fail-over of jms provider and other funcionality such as user sessions.

I think option 2 is the most easy to implement for you. Having 2 seperate systems access the same database could cause some complications with DB locking which are hard to troubleshoot.

Regards,

Nathan