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Thread: #rbs?

  1. #1
    Join Date
    Dec 2003
    Location
    Buenos Aires, Argentina
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    86

    Question Unanswered: #rbs?

    Hi everybody. One issue about RBS.
    According Ora docs and other metalink papers, the number of RBS is 1 per 4 users, and is not recommendable to have more than 40 RBS (160 users).
    But what happend if I have, for example, 1000 simoultaneous users?
    Thanks!
    Manf

  2. #2
    Join Date
    Dec 2003
    Location
    Noida, India.
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    171

    Re: #rbs?

    Do you have 1000 users or 1000 connections?


    Originally posted by Manf
    Hi everybody. One issue about RBS.
    According Ora docs and other metalink papers, the number of RBS is 1 per 4 users, and is not recommendable to have more than 40 RBS (160 users).
    But what happend if I have, for example, 1000 simoultaneous users?
    Thanks!
    Manf
    Oracle can do wonders !

  3. #3
    Join Date
    Dec 2003
    Location
    Buenos Aires, Argentina
    Posts
    86

    Re: #rbs?

    Originally posted by cmasharma
    Do you have 1000 users or 1000 connections?
    Not yet, but I have 500 users average and growing.

  4. #4
    Join Date
    Sep 2003
    Location
    Milan, Italy
    Posts
    130

    Re: #rbs?

    Originally posted by Manf
    According Ora docs and other metalink papers, the number of RBS is 1 per 4 users, and is not recommendable to have more than 40 RBS (160 users).
    It was suggested to have 4 *concurrent* TRANSACTIONS per rollback segments, not connections or sessions.

    That magic number comes from the parameter TRANSACTIONS_PER_ROLLBACK_SEGMENT (check the Oracle Reference Guide) which defaulted to 4 and now (9i) defaults to 5.

    The goal is just to avoid contention on the rollback segment header, which is heavily updated when you modify the database. Having more segments will obviously spread the load and alleviate this "problem". But knowing the "correct" number of rbs is a matter of monitoring the database - the idea of dividing #concurrent transactions by 4 or by 5 is just a rough estimate, not an unbreakable rule.

    hth
    al

  5. #5
    Join Date
    Dec 2003
    Location
    Buenos Aires, Argentina
    Posts
    86

    Re: #rbs?

    Originally posted by alberto.dellera
    It was suggested to have 4 *concurrent* TRANSACTIONS per rollback segments, not connections or sessions.

    That magic number comes from the parameter TRANSACTIONS_PER_ROLLBACK_SEGMENT (check the Oracle Reference Guide) which defaulted to 4 and now (9i) defaults to 5.

    The goal is just to avoid contention on the rollback segment header, which is heavily updated when you modify the database. Having more segments will obviously spread the load and alleviate this "problem". But knowing the "correct" number of rbs is a matter of monitoring the database - the idea of dividing #concurrent transactions by 4 or by 5 is just a rough estimate, not an unbreakable rule.

    hth
    al
    Thanks for your tips!!!

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