Thursday 19 June 2014

APPS DBA INTERVIEW QUESTIONS


Q. How would you know that your applications setup is a using shared APPL_TOP configuration ?
- If you apply a patch, it should be visible on all nodes (APPL_TOP) which are part of shared APPL_TOP configuration.
- Since APPL_TOP is on a shared disk, create file in APPL_TOP from one node, it should be visible from other nodes.
To Know more on shared APPL_TOP check metalink note
243880.1  Shared APPL_TOP FAQ
384248.1  Sharing The Application Tier File System in Oracle E-Business Suite Release 12
233428.1  Sharing the Application Tier File System in Oracle Applications 11i


Q. What is difference between shared APPL_TOP and shared Application Tier ?
- In shared APPL_TOP, only APPL_TOP & COMMON_TOP are shared across multiple middle tier where as in Shared Application Tier ORACLE_HOME (Middle Tier 806 & iAS directory) are also shared except configuration files (iAS).

Q. How would you know about which servers are running on a particular node ?
i) Check value of variable, isConcisWebisFormsisAdmin in CONTEXT FILE
ii) Control scripts – only the services which are running from particular node will have the corresponding control scripts installed on that node (This answer is partially right, depending on AD & FND version).
iii) Check FND_NODES table


Q. Adsplice – I have a 3 node installation: 1. Forms 2. Web 3. CM/Admin/Reports
and DB which node I will run the adsplice on, to install a new product ?
– You must run adsplice on all nodes (APPL_TOPs) so that application utilities recognize new product.

Q. There are four Oracle Databases running on a mahine. How would you check the location of their Oracle Homes ?

- Check entry in oratab file
– If you know any other way to find out update it as comment

Q. How would you check if the tablespace is in backup mode ?
- Check in v$backup
SQL> SELECT d.tablespace_name, b.status FROM dba_data_files d, v$backup b
WHERE d.file_id = b.FILE# and b.STATUS = ‘ACTIVE’ ;

Q. When Database is up, listener is up. listener.ora and tnsnames.ora both are configured properly, still client is not being able to make a connection to the database. What may be the possible issues ?
– Firewall blocking db port between client and server
– Authentication restricted in sqlnet.ora (Client allowed from only selected machines)


Q. What is “Custom TOP” in apps ?
- Custom top is similar to other tops under APPL_TOP but containing custom (client) specific functionality. Apps DBA need to define custom TOP and register all custom code under CUSTOM TOP


Q. if you find that under $FND_TOP/secure directory, there are many .dbc files, how would you know which is the correct one ?– System picks up dbc file based on profile option value “Applications Database ID


Q. Why do we get error when we run “opmnctl status” from “$INST_TOP/ ora/ 10.1.3/ opmn/ bin” where as $ADMIN_SCRIPTS_HOME/adopmnctl.sh works ?
For those who are new to Oracle Apps R12 or OPMN
ORACLE_HOME in application tier in Applications R12
Similar to Oracle Applications 11i, there are two ORACLE_HOMEs (but of version 10g) on application tier (three in total including database)
i) 10.1.3 (10g R3) for Web-Apps Tier (HTTPOC4J – oacore, oafm, forms)
ii) 10.1.2 (10g R2) for forms & reports server
For technical differences between 11i & R12 click here


What is opmnctl/adopmnctl ?
OPMN - Oracle Process Manager & Notification Server is component in Oracle Application Server (10g) to manage (start/stop/status) Application Server components (HTTP, OC4J)
adopmnctl - is wrapper around opmnctl to manage application server (10g R3 & 10g R3) in Oracle Applications (EBS) R12 . More information here
.
What is INST_TOP in Oracle Apps ?
INST_TOP
 denotes new TOP in Apps R12 INSTANCE_HOME, more informationhere . INSTANCE_HOME contains scripts, log and configuration files .
.  
Now back to question Why do we get error when we run “opmnctl status” from “$INST_TOP/ ora/ 10.1.3/ opmn/ bin” although we get output on running$ADMIN_SCRIPTS_HOME/ adopmnctl.sh
When you run opmnctl status from $INST_TOP/ora/10.1.3/opmn/bin you get error like below
$ ./opmnctl status
Error reading opmn.xml
Message:{$INST_TOP/ora/10.1.2/opmn/conf/opmn.xml (No such file or directory)}
Filename:{$INST_TOP/ora/10.1.2/opmn/conf/opmn.xml}
FileContent:{}
.
This is because when you run “opmnctl status” from $INST_TOP/ora/10.1.3/opmn/bin,opmnctl executable picks up OPMN config file (opmn.xml) from $ORACLE_CONFIG_HOME/opmn/conf/opmn.xml and $ORACLE_CONFIG_HOME by default is set to 10.1.2  ORACLE_HOME .
             It is still possible to display status using $INST_TOP/ora/10.1.3/opmn/bin/status but first set $ORACLE_CONFIG_HOME to 10.1.3  (This can be done by executing 10.1.3 environment file i.e. $INST_TOP/ora/10.1.3/$SID_$hostname.env )
Why don’t you get above error by running $ADMIN_SCRIPTS_HOME/ adopmnctl.sh ? adopmnctl.sh calls $INST_TOP/ora/10.1.3/$SID_$hostname.env and sets $ORACLE_HOME and $ORACLE_CONFIG_HOME to 10.1.3 related executable and configuration files. adopmnctl.sh is correct script to manage services (start/stop/status) controlled by OPMN in R12.

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