Oracle MVA

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Archive for the ‘RAC’ Category

Configuring Fusion Middleware JDBC Data Sources Correctly

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The out of the box settings for a data source in a random Fusion Middleware product (SOA, WebCenter, OIM, etc. they are all alike) JDBC properties contains guesses about your environment and usage. Same goes for the settings required by RCU when installing a repository.

For a customer I recently wrote a document explaining which settings to set on the database and in WebLogic when configuring data sources for a Fusion Middleware product for production usage while connected to a RAC database.

The document assumes you are running a 11.2 RAC and WebLogic 10.3.4 or newer. Here’s the document:

Configure JDBC data sources for RAC

Hope this helps.

BTW: if you already downloaded the document, please download it again. Seems I made an error in the distributed lock area.

Written by Jacco H. Landlust

November 17, 2012 at 1:13 am

Contention problems with AQ

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While doing a routine checkup I found that four processes are eating up CPU’s on one node of a two (2) node RAC cluster. These processes are ora_q000_SID2, ora_Q001_SID2, ora_Q002_SID2 & ora_Q003_SID2. This suggests there is some extra activity with AQ on the SID2 instance. (This is a RDBMS RAC running on 64-bit OEL 4.7, CRS and ASM on

So first thing I investigated were the queues:

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Written by Jacco H. Landlust

February 26, 2010 at 10:11 am

Posted in RAC, RDBMS

px-slaves and gv$session

with 2 comments

While troubleshooting some problem on a RAC database for a customer, I queried gv$session. I knew I was the only user logged in with my username, but somehow I found four rows in gv$session for my one session. Some further investigation told me this:

MY_USER@SOME_DB SQL> select inst_id, username
  2    from gv$session
  3   where username = ‘MY_USER’;

———- ——————–
         1 MY_USER
         1 MY_USER
         2 MY_USER
         3 MY_USER

Obviously I was annoyed by the fact that four results came back from gv$session, even though I was the only person logged in. Luckily my colleague Jeroen explained to me that I was completely overlooking the fact that querying gv$session actually invokes a parallel query over the complete RAC:

MY_USER@SOME_DB SQL> select inst_id, osuser, program
2 from gv$session
3 where username = ‘MY_USER’;

———- ——————– ————————————————–
1 LandlustJH (TNS V1-V3)
1 LandlustJH (PZ99)
2 LandlustJH (PZ99)
3 LandlustJH (PZ99)

Somehow I could have know this…. Somehow this also might explain why sometimes EM gives four audit alerts after one login. Anyway, this post is to share this with the world: remember that sometimes results from Oracle seem wrong, but in fact they’re not.

P.S.: and call Jeroen if you need a real pro on the job 😉

Written by Jacco H. Landlust

November 11, 2009 at 8:31 pm

Posted in RAC

BPEL dehydration store and HW contention

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Today I spent some time on fixing performance issues with the BPEL dehydration store. The database is a three (3) node RAC cluster, running RBDMS on ASM BPEL connects to a service name that has one (1) preferred instance and two (2) available instances.

HW contention usually means: trouble with lobs. Just to be sure, I started to check metalink. First of all I discovered I had to set event 44951 to fix bug 6376915 (setting an event without restarting the database means setting events =, next set the event in the spfile). This didn’t clear my HW contention problems though.  What did solve the problems, was moving the lobsegments to a separate tablespace. Here’s the script I used to move the lobsegments (with some extra segment space shrinking):

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Written by Jacco H. Landlust

September 17, 2009 at 9:26 pm

Posted in BPEL, RAC, RDBMS