Installation guide

6.2 Changing the DDR Database
When you make a change to the operating parameters or characteristics of
a SCSI device, you must describe the changes in the /etc/ddr.dbase file.
You must compile the changes by using the ddr_config -c command.
Two common reasons for changes are:
• Your device deviates from the SCSI standard or reports something
different from the SCSI standard
• You want to optimize device defaults, most commonly the
TagQueueDepth parameter, which specifies the maximum number of
active tagged requests the device supports
You use the ddr_config -c command to compile the /etc/ddr.dbase
file and produce a binary database file, /etc/ddr.db. When it is notified
that the file’s state has changed, the kernel loads the new
/etc/ddr.dbase file. In this way, the SCSI CAM I/O subsystem is
dynamically updated with the changes that you made in the
/etc/ddr.dbase file and the contents of the on-disk database are
synchronized with the contents of the in-memory database.
Use the following procedure to compile the /etc/ddr.dbase database:
1. Log in as root or become the superuser.
2. Enter the ddr_config -c command, for example:
# /sbin/ddr_config -c
#
When the prompt is displayed, the compilation is complete. If there are
syntax errors, they are displayed at standard output and no output file is
compiled.
6.3 Converting Customized cam_data.c Information
You use the following procedure to transfer customized information about
your SCSI devices from the /sys/data/cam_data.c file to the
/etc/ddr.dbase text database. In this example,
MACHINE is the name of
your machine’s system configuration file.
1. Log on as root or become the superuser.
2. To produce a summary of the additions and modifications that you
should make to your /etc/ddr.dbase file, enter the ddr_config -x
command. For example:
# /sbin/ddr_config -x MACHINE > output.file
Administering Devices with Dynamic Device Recognition 6–3