IV16270: GPFS DOC UPDATE REQUEST- PREFETCHTHREADS AND WORKER1THREADS

 

APAR status

  • Closed as documentation error.

Error description

  • The GPFS Concepts, Planning and Installation Guide for
    3.3 and 3.4, Chapter 9 Configuring and tuning your system
    for GPFS, section "GPFS use with Oracle", states the
    following:
    
    Set the GPFS worker threads through the mmchconfig
    prefetchThreads command to allow the maximum parallelism
    of the Oracle AIO threads:
    * This setting can be as large as 548.
    The GPFS prefetch threads must be adjusted accordingly
    through the mmchconfig prefetchThreads command as the sum
    of those two classes of threads must be 550 or less.
    * When requiring GPFS sequential I/O, set the prefetch
    threads between 50 and 100 (the default is 64), and set
    the worker threads to have the remainder
    ...
    In APAR IZ63080 for 3.3 these limits were
    increased.  The prefetchThreads + worker1Threads +
    nsdMaxWorkerThreads upper limit for AIX is 1500, for
    Linux 64bit and Windows the limit is 500.
    

Local fix

Problem summary

  • In The GPFS Concepts, Planning and Installation Guide
    Chapter 9 Configuring and tuning your system
    for GPFS, section "GPFS use with Oracle", the following
    is stated:
    
    Set the GPFS worker threads through the mmchconfig
    prefetchThreads command to allow the maximum parallelism
    of the Oracle AIO threads:
    
    * This setting can be as large as 548.
     The GPFS prefetch threads must be adjusted accordingly
     through the mmchconfig prefetchThreads command as the sum
     of those two classes of threads must be 550 or less.
    * When requiring GPFS sequential I/O, set the prefetch
     threads between 50 and 100 (the default is 64), and set
     the worker threads to have the remainder
    
    In APAR IZ63080 for GPFS 3.3, these limits were
    increased.  The documentation needs to be updated
    to reflect the new limits.
    

Problem conclusion

  • GPFS Concepts, Planning and Installation Guide
    Chapter 9 Configuring and tuning your system
    for GPFS, section "GPFS use with Oracle" has been
    updated with the following:
    
    Set the GPFS worker threads through the mmchconfig
    worker1Threads command to allow the
    maximum parallelism of the Oracle AIO threads:
    
    * This setting can be as large as 548.
     Adjust the GPFS prefetch threads accordingly through
     the mmchconfig prefetchThreads command, as the sum
     of those two classes of threads must be one of the
     following:
     - For AIX: 1500 or less
     - For Linux: 500 or less
     - For Windows: 500 or less
    
    * When requiring GPFS sequential I/O, set the prefetch
     threads between 50 and 100 (the default is 72),
     and set the worker threads to have the remainder.
    
    
    GPFS Administration and Programming Reference
    
    The following attributes for the mmchconfig command
    have been updated:
    
    worker1Threads
    Controls the maximum number of concurrent file operations
    at any one instant. If there are more requests than that,
    the excess will wait until a previous request has finished.
    This attribute is primarily used for random read or write
    requests that cannot be pre-fetched, random I/O requests,
    or small file activity. The default value is 48.
    The minimum value is 1. The maximum value of prefetchThreads
    plus worker1Threads is 1500 for AIX, 500 for Linux and
    Windows.
    
    
    prefetchThreads
    Controls the maximum possible number of threads dedicated
    to prefetching data for files that are read sequentially,
    or to handle sequential write-behind.
    
    Functions in the GPFS daemon dynamically determine the
    actual degree of parallelism for prefetching data.
    The default value is 72. The minimum value is 2.
    The maximum value of prefetchThreads plus worker1Threads
    is 1500 for AIX, 500 for Linux and Windows.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV16270

  • Reported component name

    GPFS/AIX5L V3

  • Reported component ID

    5765G66AP

  • Reported release

    350

  • Status

    CLOSED DOC

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Submitted date

    2012-02-28

  • Closed date

    2012-03-29

  • Last modified date

    2012-03-29

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Publications Referenced
GA76041300 SA23222100      

Fix information

Applicable component levels

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Document information


More support for:

General Parallel File System for Linux on POWER

Software version:

350

Operating system(s):

AIX

Reference #:

IV16270

Modified date:

2012-03-29

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