MC/SG - WebLogic Integration

[Van Poelvoorde]

Hi,

I've quite some experience with MC/ServiceGuard, but a rookie in WebLogic.
Is there anyone who has some experience in implementing WebLogic Server (version 6.1) in an MC/ServiceGuard cluster?

For the moment I want to create a 2 node cluster with on one node an Oracle DB package and on the other node a WebLogic application in another package. So, I have two packages. Do I need, e.g. a thrid one, for the WebLogic Server?
What about the built-in cluster possibilities of WebLogic Server itself, is it possible to use those together with the MC/SG cluster configuration?

Please, some help is necessary here.

Can anyone tell me, how to approach this.


Many thanks in advance,

Wim Van Poelvoorde

[Stephen Doud]

We have no implementation strategy for Weblogic packages at the repository.
Perhaps you can check with the vendor for strategy?

-Stephen

[Jeff Schussele]

Hi Van,

We successfully set up a WebLogic cluster under a MC/SG cluster simply by defining the app pkg that used WL under MC/SG to assert the "main" WL IP as well as the WL cluster IPs when the pkg was brought up under MC/SG. Was not what you would call elegant but worked well & presented no major problems.
Failover worked flawlessly.
I can't remember what the max # of IPs that an MC/SG pkg can assert - 16 I think - but we never reached a limit & we were bringing up 6-10 per pkg.
The multicast features of WL were another problem that the app dev team never did seem to get a handle on though......

HTH,
Jeff

[Jeff Schussele]

Van,

I should have mentioned we also were able to do some load-balancing by setting up multiple WL enabled app pkgs and spreading the cluster IPs around to these pkgs & running different pkgs across different servers. Then we set up a round-robin in DNS that would distribute the load around when the users would use the round-robin IP - only.
Of course there was always the "savvy" user who would use an individual IP in the rr group - essentially defeating the load-balancing.......

Rgds,
Jeff

[Bryan_21]

Jeff Schussele:

Can you provide me with more details on the WLS integration with MCSG.

- Was WLS installed on both nodes or in the package?

- What changes did you have to make to WLS (it uses localhost to communicate).

Thanx Bryan

[Jeff Schussele]

Hi Bryan,

Actually we had a 3-node cluster.
And Yes WLS was installed & licensed on all 3 servers. The MC/SG pkgs would bring up the virtual (cluster) IPs.
Was designed so that the ranges for the WLS cluster IPs were consecutive & the MC/SG pkgs were configured to bring up portions of the cluster IPs.
Also the pkg(s) would bring up the WLS server (virtual) IP as well.
The pkgs would ALWAYS be started prior to the WLS or apps being started.

EX the cluster range was ~.20 -> ~.43

server1 was licensed for ~.20 -> ~.43 & the host IP
server2 was licensed for ~.20 -> ~.43 & the host IP
server3 was licensed for ~.20 -> ~.43 & the host IP

Pkg1 was asserting ~.20 ~.23 ~.26 ~29 ~.32 ~.35 ~.38 ~.41 cluster IPs & the WLS server1 IP
Pkg2 was asserting ~.21 ~.24 ~.27 ~.30 ~.33 ~.36 ~.39 ~.42 & the WLS server2 IP
Pkg3 was asserting ~.22 ~.25 ~.28 ~.31 ~.34 ~.37 ~.40 ~.43 & the WLS server3 IP

DNS round-robin entry contained the ~.20 -> to -> ~.43 range
Users connected to the RR hostname & DNS would "dole out" the IP to the client which would point to one of the diff servers.

This way failover would not "break" the cluster IPs up & if absolutely necessary a single node could run 2/3 or even the entire cluster...although it would have to be properly sized to do so & was a "worst-case" situation.

As I was an SA in this & not a developer there, I cannot verify actual communications or if any mods were actually made.
WebLogic was installed normally & in it's conf file the hostname - not virtual- for the server was designated.
I know the pkg the developers wrote would actually start the WLS & it's apps if necessary - not an rc script. The apps they developed had conf files to designate what the virtual WLS IP/hostname was as well as the cluster IPs it would contain.
And as stated MC/SG & it's pkgs were always started first. The WLS server1(2,3) IPs were to indicate which server had which pkg(s) running. I assume that a socket was formed on connection & depending on which IP the client contacted - would determine to which server the client connected.

HTH,
Jeff

[Bryan_21]

I guess RR is fine in the DNS if and only if (iff) the application is stateless.

Bryan