Case study 28: How to grant MLOCK permission during async i/o settings
  • Platform: HP-UX 11
  • Sybase ASE version: All
  • Background story: In document describing preinstallation steps for Sybase on HP-UX, there is a paragraph saying this:

    To optimize asynchronous I/O and to prevent the paging of shared memory, you must grant MLOCK permissions before you install Adaptive Server.
    To grant MLOCK permissions to a group, enter:
    /etc/privgrp add mlock
    /etc/setprivgrp MLOCK

    For someone who is not so experienced with UNIX-like systems, this could be a problem what should be done in order to follow this step.
    Here is more detailed explanation of this step.
  • Task: Describe the process of granting MLOCK permission in more details
  • Solution:
    1. Log in to the HP-UX machine as the root user.
    2. Using any text editor, open the /etc/privgroup file, or create it if necessary.
    3. Add or edit the following line, which begins with the name of the dba group(group in which user which is going to install Sybase exsists - usually sybase user), specifying the privilege MLOCK:

      dba MLOCK

      Note: You must use only one line to specify the privileges for a particular group in this file. If the file already contains a line for the dba group, then add the MLOCK privilege on the same line.
    4. Save the file, and quit the text editor.
    5. Enter the following command to grant the privileges to the dba group:

      /usr/sbin/setprivgrp -f /etc/privgroup

    6. Enter the following command to verify that the privileges are set correctly:

      /usr/sbin/getprivgrp dba

      For more details, how async i/o could be turned on on Sybase, You can follow this Oracle (sic!) document .

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