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Thread: 32bit vs 64bit

  1. #1
    Join Date
    Jan 2007
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    Unanswered: 32bit vs 64bit

    hi,

    we are running db2 v8 64 database in aix 5. we have upgraded db2 from 32bit to 64bit as well as OS also.

    What is the performance difference between 32 and 64 bit?
    What are all the parameters need to be changed in order to utilize the 64bit?

    can anyone suggest.

    regards

    sanjai

  2. #2
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    The main difference is that you can address more memory in a 64 bit DB2 instance than in 32 bit. With 32 bit, you are limited to about 2GB of memory or less per database. This has its biggest impact on bufferpool memory. If your database size is less than 1 GB, then it probably does not make any difference since you could fit the entire database in 1GB bufferpools on a 32 bit system.

    In version 9, only 64 bit DB2 is available for AIX and most other 64 bit operating systems.

    Contrary to popular belief, a 64 bit DB2 system will not run faster than a 32 bit DB2 system if both systems had the same size bufferpools and other memory allocations.

    A 64 bit DB2 system needs a little more disk space to store the larger 64 addresses for things like RID's, etc.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  3. #3
    Join Date
    Mar 2007
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    35
    Quote Originally Posted by Marcus_A
    The main difference is that you can address more memory in a 64 bit DB2 instance than in 32 bit. With 32 bit, you are limited to about 2GB of memory or less per database. This has its biggest impact on bufferpool memory. If your database size is less than 1 GB, then it probably does not make any difference since you could fit the entire database in 1GB bufferpools on a 32 bit system.

    In version 9, only 64 bit DB2 is available for AIX and most other 64 bit operating systems.

    Contrary to popular belief, a 64 bit DB2 system will not run faster than a 32 bit DB2 system if both systems had the same size bufferpools and other memory allocations.

    A 64 bit DB2 system needs a little more disk space to store the larger 64 addresses for things like RID's, etc.
    Hi Marcus_A,
    do you mean (client-server system) 32 bit client V9 does not work with 64 bit server?

  4. #4
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    Quote Originally Posted by jsmit
    Hi Marcus_A,
    do you mean (client-server system) 32 bit client V9 does not work with 64 bit server?
    No, that is not what I said.

    Starting with DB2 9.1 server, the server code is only available in 64-bit versions on the following operating systems:

    AIX
    Solaris
    HP/UX

    Linux and Windows have both 32 and 64 bit versions.

    You can run a 32 bit Linux or Windows client connecting to a 64 bit server, but there are no 32 bit clients for AIX, Solaris, and HP/UX starting with V9.1.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  5. #5
    Join Date
    Jan 2003
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    1,605
    Hi,
    in year 2005 as IBM business partner I had a privilege to be part of testing team from my company to test performance before purchase of DB2 on "Linux System z" comparing 31-bit to 64-bit of computer in IBM lab. On System z there is no 32-bit system there was 31-bit only. That time there was 8.2 version of database. We have made several tests and the results was something like this:
    a) individual simple select SQLs execution time: 31-bit faster for 5%
    b) complicated select SQLs (join of several tables): 31-bit system faster for 8%
    c) inserting million records with SQL: 31-bit system faster for 7%
    d) 100 concurrent application (using batch files) inserting each 30 records into the same table: 64-bit system was faster for 70%

    All the test had the same dbm/db configs.

    Conclusion: single SQL to single SQL comparison was faster on 31-bit, but using complicated environment could result in much better performance in 64-bit. At that time we decided to purchase 64-bit system.

    Hope this helps,
    Grofaty

  6. #6
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    I don't think that DB2 on a 31 bit Linux System z is in any way comparable to running DB2 on an Intel/AMD Linux box.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

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