Cluster Apex MS's across multiple nodes for load balancing?

Question

Can Cluster Apex MS's across multiple nodes for load balancing? If Yes/No, any supportive doc's will be much appreciated.
Here is what I did ..........
I tried multiple MS's on different nodes for Apex Domain (clustered)
Deployed apex.war, i.war with targets pointing to cluster.
Apex listener techstack is shared filesystem $HOME/apex, where apex-config.xml and bdb are available
Anyone of the MS's whichever started up first is locking up bdb and 500 server shows up when internal workspace is being launched with host specific url, where as it works fine for the host which actually locked up bdb (first MS that was started)
2nd MS shows errors as below in log files ..
Caused By: com.sleepycat.je.EnvironmentLockedException: (JE 4.0.103)$HOME/apex/bdb The environment cannot be locked for single writer access. ENV_LOCKED: The je.lck file could not be locked. Environment is invalid and must be closed.
Its expected behavior until here .....
++++ I tried something to get it working ++++
Whilst both MS's are up and running, delete $HOME/apex/bdb but let apex-config,xml be as it is...now the internal workspace urls for both hosts work fine. I logged into host specific urls and navigated, created/edited users.,etc and it is all looking good but it did not create new bdb directory under $HOME/apex ...!!
Having said its working fine, the same issue repeats after the MS's bounce. So I did put a command line to delete bdb dir once the MS comes up to avoid the issue but really not sure if this is the right way at all?
Geek's ...awaiting your advice!!

Answer 1

Hey there,
I managed to fulfill my requirement..
If its a cluster on same machine or across machines, this should work
1. Login to machine, cd $DOMAIN_HOME
2. mkdir -p Apex_lsn_config/AdminServer Apex_lsn_config/<MS1> Apex_lsn_config/<MS2> # MS1 and MS2 are the Managed Server names as appropriate
#If you are planning for cluster spawning MS's across machines, make sure you create the dir's on step 2 for each machine respectively. (in my case $DOMAIN_HOME is not shared)
3. Copy apex-config.xml from the /tmp/apex or whatever location you have it currently to Apex_lsn_config/<MS1> Apex_lsn_config/<MS2>
4. cd $DOMAIN_HOME/bin; cp -p SetDomainEnv.sh SetDomainEnv.sh.orig #Backup the file
5. Append -Djava.io.tmpdir in SetDomainEnv.sh as below for JAVA_OPTIONS # Do it on both machine if you are not sharing DOMAIN_HOME and planning cluster across machines
-Djava.io.tmpdir=$DOMAIN_HOME/APEX_CONFIG/${SERVER_NAME}
Hint: Search for "iterativeDev" and append the same line with -Djava.jo.tmpdir
6. Modify "java.io.tmpdir" from the web.xml file of apex.war as below and re-deploy the war
<context-param>
     <param-name>config.dir</param-name>
     <param-value>${java.io.tmpdir}</param-value>
</context-param>
7. Bounce Weblogic Admin and Manged Servers. Make sure to tail the Managed Server log to see apex-config.xml is picked from the new location.
8. Brew a Coffee for yourself :)
- You find the instructions on creating a cluster from weblogic documentation, the steps mentioned above are only to overcome the bdb locking issue whilst creating a cluster.
Did it help?
Edited by: Oratime on Mar 25, 2013 2:44 AM