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  1. #1
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    Jan 2003
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    Unanswered: Federated access is limited to 3 connurent connections? How to set more connections?

    Hi,
    On database DB2 v8.2 fp11 for Linux on S/390 is federated access to DB2 v7.4 for VSE on S/390. Applications using federated access are working fine if 3 connections or less are used. But if forth connection is trying to establish connection to remote database, Linux database returns the following error:
    Code:
    SQL30081N  A communication error has been detected.  Communication protocol
    being used: "unknown ".  Communication API being used: "unknown ".  Location
    where the error was detected: "unknown ".  Communication function detecting 
    the error: "unknown ".  Protocol specific error code(s): "unknown ", "unknown 
    ", "unknown ".
    I have tested this connection with batch file witch creates 4 connection. First 3 connection are getting the result as they should, but forth connection gets above error.

    Is there any settings that limits federated access concurrent users to remote database?

    Thanks,
    Grofaty
    Last edited by grofaty; 01-25-07 at 08:38.

  2. #2
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    There is no such limitation in the DRDA wrapper, which is the DB2 component that talks to DB2 on z/OS. You should try to see which connections are established on the DB2 z-Server...
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  3. #3
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    Jan 2003
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    stolze, I was discussing to DBA on zServer and he pointed out that on zServer there are 30 remote users available. And what is more there is no error message on zServer DB2 console. By the error message it look likes there is a problem Linux site (federation or connect), because "a communication error" as I understand it means there is no response by zServer - connection is not even reached to the point zServer could responsed. What I dislike the most is "unknown" seven times. So don't have idea where to start looking... Any idea where to look for this limitation? Do you think there is a bug?
    Thanks,
    Grofaty
    Last edited by grofaty; 01-26-07 at 02:25.

  4. #4
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    First thing is to look at the output of the "db2diag" tool for the time frame when you attempt the connection.

    How have you tested the connection on the command line?
    How many open connections do you have the DB2 on z subsystem before/while the connection attempt fails?
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  5. #5
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    Stolze, there is no additional info in db2diag.log.

    My command line batch file looks like:
    Code:
    start db2cmd /i /c /w db2 -tf sqlfile1.sql
    start db2cmd /i /c /w db2 -tf sqlfile2.sql
    start db2cmd /i /c /w db2 -tf sqlfile3.sql
    start db2cmd /i /c /w db2 -tf sqlfile4.sql
    sqlfiles have the following commands:
    Code:
    connect to database_name
    select * from big_table
    Big table is used to be absolutely sure all connections 3 connections are used before fourth connection is attempting to establish connection to db2 z-server.

    On Z system there are 25 available connections. And only 3 are used.

    Do you have any idea where to look for?
    Thanks,
    Grofaty
    Last edited by grofaty; 01-29-07 at 02:06.

  6. #6
    Join Date
    May 2006
    Posts
    82
    Hi,

    Recently i was working on cross loader and i remember i was going thru the DRDA concepts. I tried to find that link and unfortunately i couldn't find that as of now. I will search it and will let you know.

    My understanding was that.
    While installing and enabling the DDF they have an option where they can set the no of ACTIVE users that can be connected at any given point of time.
    Apart from this there were many other things that were talking about SYSLUNAMES,SYSLOCATIONS,SYSUSERNAMES, etc and CDB(optional for security) . I'm sorry i could address much since i dont remember. I think i should search for that link now.
    But am sure this is some thing with the configuration of DRDA connections. May be on your end or on the other end. I will get back to you with much information shortly. Thank you...Please feel free to correct me if am wrong. I'm a programmer, not a DBA or SYSADMIN -

  7. #7
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    vini_srcna,
    it looks like there is a problem between db2 Linux and db2 VSE and this problem is on my humble opinion on db2 Linux site, because db2 VSE does not report any error on db2 console.

    I would be very happy if you could provide link as you mentioned.

    Thanks,
    Grofaty

  8. #8
    Join Date
    May 2006
    Posts
    82
    Grofaty, Finally i found the link. I dont know to howfar it would be helpfull for you. It talks about the installation on Z/OS. Thanks

    http://manuals.sybase.com/onlinebook...kTextView/3042

  9. #9
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    Jan 2003
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    vini_srcna, as I see this documentation is for db2/zOs. My system in VSE for zSeries computer. As I see from system table names there are not the same names. I will send this document to db2_VSE admin and I hope he can find something useful from this post.

    By the way, which command should be the one to increase max users connections from 3 to more then 3?
    Thanks,
    Grofaty
    Last edited by grofaty; 01-29-07 at 08:45.

  10. #10
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    Quote Originally Posted by grofaty
    there is no additional info in db2diag.log.
    What's your DIAGLEVEL set to? It should be 4 to get as much information as possible.

    On Z system there are 25 available connections. And only 3 are used.
    How exactly have you verified that?

    You could dump the SQLCA for your SQL statements (db2 -a).
    Also, a db2 trace could help to figure out where the error is detected.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

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