Preallocating space for Quick I/O files using the setext command
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Preallocating space for Quick I/O files using the setext command

As an alternative to using the qiomkfile command, you can also use the VxFS setext command to preallocate space for database files.

Before preallocating space with setext, make sure the following conditions have been met:

Prerequisites

  • The setext command requires superuser (root) privileges.

Usage notes

  • You can use the chown command to change the owner and group permissions on the file after you create it.

    See the setext (1M) manual page for more information.

To create a Quick I/O database file using setext

  1. Access the VxFS mount point and create a file:
    		# cd /mount_point
    		# touch .filename
  2. Use the setext command to preallocate space for the file:
    		# /opt/VRTS/bin/setext -r size -f noreserve -f chgsize  \
		.filename
  3. Create a symbolic link to allow databases or applications access to the file using its Quick I/O interface:
    		# ln -s .filename::cdev:vxfs: filename
  4. Change the owner and group permissions on the file.

    For example, for DB2:

    		# chown user:group .filename
    # chmod 660 .dbfile

    For example, for Sybase:

    		# chown sybase:sybase .filename
    		# chmod 660 .filename
  5. To access the mountpoint for the database:

    For example, for /db01, create a container, preallocate the space, and change the permissions:

    # cd /db01
# touch .dbfile
# /opt/VRTS/bin/setext -r 100M -f noreserve -f chgsize .dbfile
# ln -s .dbfile::cdev:vxfs: dbfile

    For DB2:

    # chown db2inst1:db2iadm1 .dbfile
    # chmod 660 .dbfile

    For Sybase:

    # chown sybase:sybase .dbfile
    # chmod 660 .dbfile
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