Server clustering...

[Brahim Bakayoko]

Hello all,
How do I cluster several application servers for load balancing? How do I configure the cluster's IP?
I have been playing around with websphere deployment manager, but I have hit a wall.
Is clustering for load balancing done at the OS level (windows cluster)?
I have created a cluster in deployment manager, but it seems to function only for deployment administrative purposes.
Thanks!

[Kyle Brown]

Load balancing of HTTP requests occurs at the HTTP Server plugin level. If you want to have several HTTP Servers be load balanced (e.g. spray requests across all of them) that is what the edge components of WebSphere ND are for.
I strongly suggest you go check out the WebSphere ND administration handbook redbook -- all of this is covered in detail there. It's also covered in the "getting started" portions of the InfoCenter for ND...
Kyle

[Brahim Bakayoko]

Thanks for the response Kyle.
I am reading the ND redbook (early draft april 2004) and I am using the edge components in my setup.
I have more to read, but I need some clarification before going further.
As my question above stated, I need to know more about clustering for load balancing. All have seen from creating a cluster in ND has been for deployment administration.
How do I define the IP for the cluster?

[Kyle Brown]

There is no difference. Clusters automatically do load balancing through the plugin. When you create them they fulfill both functions.
You don't define an IP for the cluster.
You have an Edge server with a single IP address that routes to 2 or more HTTP Servers that then route to 2 or more Application Servers in a cluster.
Kyle

[Brahim Bakayoko]

Thanks Kyle!
I finally figure it out. Yes, I do need a cluster IP.
The way it is configured is by installing a Loopback adapter on each server and then configuring that adapter with the chosen cluster IP.
Since I am on windows, I have to install a Microsoft Loopback Adapter as a virtual hardware then configure its properties. The load balancer actually needs that IP when you configure it. I had a feeling it was more at the OS level.
I am currently playing around with Windows Server Clustering to see if that is a better alternative to manually adding the virtual adapters.
Thanks again!

[Kyle Brown]

Brahim,
I'm not sure what you're doing, but this is NOT, I repeat, NOT the way that you set things up for WebSphere clustering! You do not have to configure loopback adapters. You do not have to use Windows clustering AT ALL and in fact it is not supported for WebSphere.
There is a standard topology for this (I apologize for the fact I have nothing to draw with here...).
Load Balancer (with one IP Address that you give out for everyone)
|
\/
HTTP Server(s) (with different IP Addresses on different machines)
loaded with the WebSphere plugin and the plugin-cfg.xml file GENERATED BY THE ADMIN CONSOLE AFTER DEFINING THE CLUSTER AND DEPLOYING YOUR APPLICATIONS
|
\/
Application Server(s) (with yet different IP addresses on different machines) defined in your cluster
The only IP address that anyone sees (from a browser) is the IP Address of the load balancer. What are you trying to do that differs from this?
Kyle

[Brahim Bakayoko]

Please look at this 55k pdf (2 pages): http://216.80.115.23:86/topology.pdf

[Kyle Brown]

Good grief. I'll take this up with the developers in the morning. This can't be right...
Kyle

[Brahim Bakayoko]

Kyle you may very well be right.
Check out these two pages from the draft: http://216.80.115.23:86/note.pdf.
I don't know what to make of it as I don't understand the whole thing well yet, but I think it shows that you might be right.
I have yet to implement the configuration as I am missing some hardware. It might take till this weekend to get the needed hardware. There is nothing like implementation to see if something works or not.
I am reading this redbook by the way: Draft Document for Review April 2, 2004 8:52 am / SG24-6198-01.
[ April 21, 2004: Message edited by: Brahim Bakayoko ]

[Kyle Brown]

Hi Brahim!
OK, so I spent a few minutes talking this over with the developer of this part of the Edge components, Chris Gage, and he actually cleared up a thing or two for me as well.
The problem is there are TWO clusters here, which is what was confusing me. There's the WebSphere ND cluster, which does not any common TCP-IP settings at all, which was what I thought you were referring to, and then there's the HTTP Server cluster (totally different) which does have the common settings referred to in the redbook.
So yes, the redbook is right in referring to the HTTP Server cluster, which is a different thing altogether. However, Chris then went on to say he wouldn't use the loopback adapter approach anyway. He'd create a Virtual IP for the cluster instead. He's also promised to answer this message with more information next week...
Kyle

[Brahim Bakayoko]

Thanks Kyle for the update!
I still haven't tried to implement the configuration as I am still waiting on the hardware.
How do I go about configuring a virtual IP for the cluster?
I am looking forward for the additional information from Chris.
I will post the result of my configuration attempt once I get the needed hardware.
Thanks again!