Direct-Coupled Disk host adapter Subsystem
The DCD subsystem consists of at least one DCD
host controller card which has at least one logical unit
attached to it.
The DCD subsystem adds support for non-SCSI devices
under SDI for use with related target drivers.
This subsystem is accessed
indirectly by opening an appropriate target driver to access
a target device that is on a DCD controller.
It is also possible to access this subsystem using the pass-through
To find the appropriate device to use, while the device
is being accessed through the target driver,
use the B_GETDEV ioctl
to get the major and minor numbers of the pass-though node.
This node can either be created or opened for use.
All of the pass-through
commands documented on the
manual page are supported by this driver.
In addition, the following commands are also
Return the pass-through major and minor numbers to the calling
utility to allow creation of a pass-through special device file.
The following commands should be used to get and set device geometry.
These return or accept the structure
dsk_geom defined in the sdi.h header file.
Return host adapter's idea of the device geometry.
This is what the system uses during the boot sequence.
This is used by certain target drivers.
Set the host adapter's idea of the device geometry.
Note that some
host adapters do not support this
ioctl and will result in an error.
Return the actual device geometry.
This is the actual as opposed to virtual device geometry.
The DCD driver halt routine that is executed during
shutdown allows the controller enough time to flush
the disk cache (if present) to disk.
Although two seconds are allowed for this flush, the
actual timeout value is an external variable in the DCD
You can modify this variable if a specific controller
needs more time to clear the cache.
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 25 April 2004