You must have permission to change file system behavior using the vxtunefs command to enable or disable Cached Quick I/O. By default, you need superuser (root)
permissions to run the vxtunefs command, but other system users do not. Superuser (root) must specifically grant database administrators permission to use this command as follows:
# chown root:db2iadm1 /opt/VRTS/bin/vxtunefs
# chmod 4550 /opt/VRTS/bin/vxtunefs
where users belonging to the db2iadm1 group
are granted permission to run the vxtunefs command. We recommend this selective, more secure approach for granting access to powerful commands.