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  • We have moved to kindly check http://onlineAppsDBA.comin future
    Shared APPL_TOP in Oracle Apps Basics
    Tuesday, September 19, 2006
    Register for R12 upgrade
    Based on lot of request I am discussing on Shared APPL_TOP & Shared Application Tier. For next few days I will start with basics of Shared APPL_TOP like
    what's is Shared APPL_TOP ?
    Advantages of Shared APPL_TOP ?
    Difference between Shared APPL_TOP & Application Tier
    Difference between Shared APPL_TOP & Staged APPL_TOP
    How to Implement Shared APPL_TOP in Oracle Apps ?

    So rather than talking too much lets start with Shared APPL_TOP & Application Tier .

    In order to understand concept of shared APPL_TOP you first need to know what is APPL_TOP & what are various other TOP's in Oracle Apps .
    Oracle Apps File System (Software ) is mainly divided in to five top level directories

    DATA_TOP : For data file (Database Tier )
    DB_TOP : Database Software 8i, 9i or 10g ( Database Tier )

    APPL_TOP : For various product tops (Application Tier )
    COMMON_TOP : for files & directories common to all products ( Application Tier )
    ORA_TOP : for iAS, Forms & Reports Component , Tech. Stack ( Application Tier )

    Why I need shared APPL_TOP ?
    If you have two/three (Multiple) Middle Tier for Large User base then you have to install APPL_TOP, COMMON_TOP & ORA_TOP equal to number of Nodes in your configuration. So if you have three middle tier then you need these three top three times & if there are n nodes you need n time these three top's .
    This result in lots of Space Requirement & bigger problem is patching so If you have 5 nodes you need to apply apps patch 5 times.
    So Oracle Came Up with solution to have single APPL_TOP which is shared across all nodes in apps. This will save space as well patch timing. This concept of sharing APPL_TOP file system across all Middle Tier Nodes is called as APPL_TOP .
    You will say if I can share APPL_TOP why Can't I share COMMON_TOP & ORA_TOP as well which are also part of Application Tier , Yes you can & this concept is called as Shared Application Tier.

    What is Shared Application Tier ?
    Sharing Application Tier ( including APPL_TOP, COMN_TOP, ORA_TOP) across all Middle Tier Nodes in configuration is called as Shared Application Tier.

    So I can say shared APPL_TOP is subset of shared Application Tier , initially shared APPL_TOP came out & based on its advantages & popularity later COMMON_TOP & ORA_TOP files were also included & entire concept is called as Shared Application Tier.

    Limitation with Shared APPL_TOP , Application Tier ?
    If you are running Apps on Windows you'll be sad to hear that its not certified with Windows Operation System. More over you can share across same operation system like Linux to Linux & Solaris to Solaris.

    More to come in next post like
    Broad Level steps of configure Shared Application Tier ..
    difference between Shared Appl_top & staged appl top

    We have moved to

    kindly check in future

    add to  ¦  digg thisDigg This  ¦  My Yahoo!My Yahoo  ¦  RedditReddit  ¦  add to BlinkListBlinkList   ¦  Furl ItFurl It  ¦  Email This Email This  ¦     Leave Your Comments
    posted by Atul Kumar @ 5:21 PM  
    • At 9:50 AM, Blogger fhasweh said…

      can u plz clerafiy the diffrence between Shared Application Tier and Shared Appl_top


    • At 10:10 AM, Blogger Atul Kumar said…

      as mentioned above, Application Tier Sharing includes sharing APPL_TOP, COMN_TOP, ORA_TOP i.e. whole application tier.

      where as shared APPL_TOP means just APPL_TOP file system sharing .

      Earlier it was just Shared APPL_TOP which later extended to sharing entire Application Tier.


    • At 2:26 PM, Blogger fhasweh said…

      thank you atul for reply but still i am not able to understand which is better for me should i go with sharde appl top or sharde file system.


    • At 2:43 PM, Blogger Atul Kumar said…

      Looking at your comments, It seems you are not clear with Shared Application Tier funda (No offence to you pls)

      shared appl top or shared file system are same thing , you achieve shared appl_top by sharing file system.

      If you are talking about shared Appl_Top & shared Application Tier , go for shared Application Tier as this is now a days followed.


    • At 9:44 AM, Blogger fhasweh said…

      sorry atul,
      i was expecting a clerificaiton on both of (shared Appl_Top & shared Application Tier what r the diffreances between them) so i can chose what to follow its not just like go for this or go for that.

      keep up the good work

    • At 11:06 AM, Blogger Atul Kumar said…

      As I mentioned shared APPL_TOP is sharing only APPL_TOP where as in shared Application Tier you share all three application tier tops i.e. APP_TOP, COMN_TOP, ORA_TOP . Earlier apps dba's were not configuring shared application tier as it was not supported . Now shared application tier is the only option left , you don't see shared APPL_TOP alone. Though people still call shared application tier as shared APPL_TOP(totally out of ignorance and becoz of similarity in concept).


    • At 8:06 AM, Blogger fhasweh said…


    • At 10:50 PM, Anonymous Ravi Bhandari said…

      Hi, I am unable to log on via Self service /oa_servlets/Appslogon page after sharing the appl top. I keep getting your session is no longer valid. Have you got a working example of migrating an existing 3 tier system to shared appl top.

    • At 10:55 PM, Blogger Atul Kumar said…

      Which note you followed ?
      I suppose some server ID or cookie is not set properly. Can you directly login to forms via dev60cgi/f60cgi ?

      Check metalink note
      233428.1 Sharing the Application Tier File System in Oracle Applications 11i as mentioned in

      Good Metalink Notes

    • At 12:26 PM, Anonymous Anonymous said…

      Hi Atul,

      Thanks for ur tremendous help
      can u plz list the differences between $ORACLE_SID and $TWO_TASK


    • At 3:59 PM, Blogger Atul Kumar said…

      TWO_TASK mocks your connection descriptor to connect to database More on this at
      Whats is TWO_TASK

      SID is to identify database Identifier i.e. If SID is set it will try to connect to database locally .

      If both SID & TWO_TASK are set , prefence will go to TWO_TASK & it will connect as network using TNS Alais defines as TWO_TASK in tnsnames.ora .


    • At 8:47 PM, Anonymous Anonymous said…

      Can you use ocfs2 for shared file system - I heard gfs stunk

    • At 9:50 PM, Anonymous Anonymous said…

      Hi Atul,

      What kind of file system is supported for shared APPL_TOP? If we use nfs, does crate a single point failure?


    • At 11:24 PM, Blogger Atul Kumar said…

      Nice Questions,

      What kind of file system is supported for shared APPL_TOP?

      Any file system which you can mount from to all nodes in shared appl_top is fine.

      If we use nfs, does crate a single point failure?
      Yes, thats true you are intoroducing single point of failure , here is alternative .

      Lets assume you have node1, node2, node3, and node4 .

      Create a filesystem share between node1 & node2 and create a snapclone/copy of that file system & mount it across node3 & node4 . After patching represent filesystem from node1,node2 to second file system on node3 & node4 .

      That way you can avoid from single point of failure.


    • At 11:29 PM, Blogger Atul Kumar said…

      Yes you can use OCFS2 as well. For others who don't know about OCFS2 , its Oracle Cluster file system .

      This can also be used to configure Standalone Database RAC but its not certified for RAC with Apps.
      For RAC with APPS ASM (Automatic Storage Management ) is recommended & certified.


    • At 2:36 AM, Blogger Tech_Whiz said…


      I tried a situation like the following:

      I had a shared file system on DB01 and DB02. I created a partition and mounted it on App01 and App02. And In this partition I created a mountpoint /app and I tried to install the APPL_TOP, COMN_TOP and ORA_TOP here...

      I had a cluster in DB01 and DB02. Hence I avoided single point of failure as I have NFS mounted in App01 using the virtual name of DB01.

      But in such a setup, my Apache was not even getting started. Is there any limitation on using Apache on NFS.

      When I went through the httpd.conf there were some highlights when the directive RootDirectory is a shared one... But I couldn't succeed...

      What do you feel about that?

    • At 8:01 AM, Blogger Atul Kumar said…

      Hi Tech whiz,
      Which version of apps you are using ?

      Did you follow any metalink note ?
      If not check if you completed task mentioned in metalink note

      233428.1 Sharing the Application Tier File System in Oracle Applications 11i

      If even after completing steps in above note then check whats error message in $OAD_TOP/conf/$CONTEXT_NAME/iAS/Apache/Apache/logs

      please note your Apache log files changed now from $IAS_ORACLE_HOME/Apache...


      $OAD_TOP/conf .....or any conf directory you created during shared Appl_top

      Now you can raise all these issues in forum dedicated to Apps DBA's at

    • At 10:29 AM, Blogger Tech_Whiz said…

      Hi Atul,

      I very much followed the same Note.

      We were with version.

      Anyways.. I'll discuss this in the forum...

      Thanks for the great work!!!

      Tech Whiz To B!!!

    • At 11:58 AM, Blogger Rahul said…

      Hi Atul,

      Can you provide me the steps of installation of Oracle 10g RAC with full structure and in explanation?

    • At 12:01 PM, Blogger Atul Kumar said…

      Check this beautifully written doc on RAC by Jeffrey Hunter

    • At 6:47 AM, Blogger vikram said…

      Hi Atul,
      I want to clarify a dowt reg whether Refresh & Clone are same are not if not what is diffe b/w them.

    • At 1:00 PM, Blogger Atul Kumar said…

      Yes, they meant to be same things , creating replica of source instance

    • At 9:23 PM, Blogger sai said…

      How can we monitor the patch progress
      in oracle 11i?

      Very Good Blog for Apps DBA's .
      Thankyou atul.

    • At 9:23 PM, Blogger sai said…

      How can we monitor the patch progress
      in oracle 11i?

      Very Good Blog for Apps DBA's .
      Thankyou atul.

    • At 9:24 PM, Blogger sai said…

      How to monitor the patch progress in oracle11i?

    • At 6:31 AM, Anonymous Anonymous said…

      Hi Atul,

      What happens internally in Shared application file how the forms,web services communicate?


    • At 10:45 PM, Anonymous Anonymous said…

      Hi Atul

      In Shared Application tier configuration, we have been seeing apache crash after generating a core file.

      Our server nodes are Solaris Zones and we have 3 web nodes for production database load balances using F5.

    • At 7:39 AM, Anonymous Anonymous said…

      have you ever implemented staged appl_top?if yes, what are the issues faced while implementation or while applying patches etc. just curious as i have to implement one soon.

    • At 7:36 PM, Anonymous Anonymous said…

      A comment regarding NFS: version 4 supports replication. You can have a setup whereby a client looks for node1 and then node2 if node1 is unavailable. However, you need a method to sync the two nodes :(

      The company I work for is creating 2 separate APPL_TOPs in separate network zones. One APPL_TOP will be accessed by outside vendors and reside in a DMZ. The other APPL_TOP will be sitting within the normal production environment along with the database.

      The vendor APPL_Top will be a subset of prodcution's APPL_TOP. This setup requires twice the maintenance because any changes to one has to be made the other.

      Is there any way to have a single APPL_TOP replicated across separate networks? Sort of like a cluster or mirror?

    • At 8:33 PM, Anonymous Anonymous said…

      This is in reference to the shared apps tier note, this is my current setup,
      Node 1: Db + Admin + CP + Reports
      Node 2: Forms + Web + Disco

      My question is when applying apps patches, do they need to be aplied on both tiers ? or since the file system is shared do we need to run auto-config ? Or just applying the apps patches on the admin tier would suffice ?


    • At 8:33 PM, Anonymous Anonymous said…

      This is in reference to the shared apps tier note, this is my current setup,
      Node 1: Db + Admin + CP + Reports
      Node 2: Forms + Web + Disco

      My question is when applying apps patches, do they need to be aplied on both tiers ? or since the file system is shared do we need to run auto-config ? Or just applying the apps patches on the admin tier would suffice ?


    • At 5:12 PM, Blogger rubeena said…

      what is merging of APPL_TOP?

    • At 3:39 PM, Blogger diptanu said…

      Can anybody tell me the command or steps to find my Appl_top is shared or not

    • At 9:04 AM, Anonymous Phani said…

      Hi Raghav,
      Yes, you need to apply a patch twice, i.e on both the nodes separetely, although it is in shared merely running it on admin tier and running of autoconfig wil not help.


    • At 9:49 PM, Blogger sunil said…

      How can i find appl top is shared or not ?

    • At 3:40 PM, Anonymous Naidu said…

      I had done the shared appplication installation on vm's. Setup is like this on 1) vm - db is installed , 2) vm - application tier -- enabled all the services 3) vm is shared of second vm appl tier -- all the services are enabled . I had doubts

      1) If I access the url of 2-VM it redirects to the 3-vm (shared) on . Can we have two differents url's opening at a time pointing to its own VM? ex. --2 VM & -- 3VM. IF I access r12apndvm url it takes to r12apnd2 url.

      2) Configured the PCP, how to check whether the configuration is working ? If I check the FNDLIBR on both v's only 1 VM is showing the FNDLIBR process (ps -ef|grep FNDLIBR ) other VM has no FNDLIBR process. Is it possible to have FNDLIBR processes on both the nodes (Vm).

    Post a Comment
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