hfs_revra_per_disk(5)                                 hfs_revra_per_disk(5)
                          Tunable Kernel Parameters



 NAME    [Toc]    [Back]
      hfs_revra_per_disk - maximum HFS file system blocks to be read in one
      read-ahead operation when sequentially reading backwards

 VALUES    [Toc]    [Back]
    Failsafe
      64

    Default    [Toc]    [Back]
      64

    Allowed values    [Toc]    [Back]
      0 to 8192

 DESCRIPTION    [Toc]    [Back]
      This tunable defines the maximum number of file system blocks to be
      read in one read-ahead operation when sequentially reading backwards.

    Who Is Expected to Change This Tunable?
      HP Field engineers, but not customers directly.

    When Should the Value of This Tunable Be Raised?
      The value of this tunable should be increased if there is a large
      number of reverse sequential file I/O on file systems with small file
      system block size.

    What Are the Side Effects of Raising the Value?
      The system will consume more memory in the buffer cache.

    When Should the Value of This Tunable Be Lowered?
      The value of this tunable should be lowered when there is a smaller
      number of reverse sequential file I/O on files systems with large file
      system block size.

    What Are the Side Effects of Lowering the Value?
      The file throughput rate will be decreased.

    What Other Tunables Should Be Changed at the Same Time?
      None.

 WARNINGS    [Toc]    [Back]
      All HP-UX kernel tunable parameters are release specific.  This
      parameter may be removed or have its meaning changed in future
      releases of HP-UX.

      Installation of optional kernel software, from HP or other vendors,
      may cause changes to tunable parameter values.  After installation,
      some tunable parameters may no longer be at the default or recommended
      values.  For information about the effects of installation on tunable
      values, consult the documentation for the kernel software being
      installed. For information about optional kernel software that was



 Hewlett-Packard Company            - 1 -      HP-UX 11i Version 2: Sep 2004






 hfs_revra_per_disk(5)                                 hfs_revra_per_disk(5)
                          Tunable Kernel Parameters



      factory installed on your system, see HP-UX Release Notes at
      http://docs.hp.com.

 AUTHOR    [Toc]    [Back]
      hfs_revra_per_disk was developed by HP.


 Hewlett-Packard Company            - 2 -      HP-UX 11i Version 2: Sep 2004