SD(4) OpenBSD Programmer's Manual SD(4)NAME
sd - SCSI disk driver
SYNOPSIS
sd* at scsibus?
#sd0 at scsibus0 target 3 lun 0 (fixed-configuration example)
DESCRIPTION
The sd driver provides support for a SCSI disk. It allows the disk to be
divided up into a set of pseudo devices called partitions. In general
the interfaces are similar to those described by wd(4).
SCSI devices have a fairly high level interface to the system and talk to
it via a SCSI host adapter (e.g., ahc(4)). A SCSI adapter must also be
separately configured into the system before a SCSI disk can be
configured.
When the SCSI adapter is probed during boot, the SCSI bus is scanned for
devices. Any devices found which answer as `Direct' type devices will be
attached to the sd driver.
PARTITIONING
On many systems disklabel(8) is used to partition the drive into
filesystems. On some systems the OpenBSD portion of the disk resides
within a native partition, and another program is used to create the
OpenBSD portion.
For example, the i386 port uses fdisk(8) to partition the disk into a
BIOS level partition. This allows sharing the disk with other operating
systems.
IOCTLS
The following ioctl(2) calls apply to SCSI disks as well as to other
disks. They are defined in the header file <sys/disklabel.h>.
DIOCGDINFO Read, from the kernel, the in-core copy of the disklabel for
the drive. This may be a fictitious disklabel if the drive
has never been initialized, in which case it will contain
information read from the SCSI inquiry commands.
DIOCSDINFO Give the driver a new disklabel to use. The driver will not
write the new disklabel to the disk.
DIOCWLABEL Enable or disable the driver's software write protect of the
disklabel on the disk.
DIOCWDINFO Give the driver a new disklabel to use. The driver will
write the new disklabel to the disk.
DIOCLOCK Lock the media cartridge into the device, or unlock a
cartridge previously locked. Used to prevent user and
software eject while the media is in use.
DIOCEJECT Eject the media cartridge from a removable device.
DIOCINQ Read the devices product information.
In addition, the scsi(4) general ioctl() commands may be used with the sd
driver, but only against the `c' (whole disk) partition.
NOTES
If a removable device is attached to the sd driver, then the act of
changing the media will invalidate the disklabel and information held
within the kernel. To avoid corruption, all access to the device will be
discarded until there are no more open file descriptors referencing the
device. During this period, all new open attempts will be rejected.
When no more open file descriptors reference the device, the first next
open will load a new set of parameters (including disklabel) for the
drive.
FILES
/dev/sdup block mode SCSI disk unit u, partition p
/dev/rsdup raw mode SCSI disk unit u, partition p
DIAGNOSTICS
None.
SEE ALSOintro(4), scsi(4), wd(4), disklabel(5), disklabel(8), fdisk(8)HISTORY
The sd driver was originally written for Mach 2.5, and was ported to
FreeBSD by Julian Elischer. It was later ported to OpenBSD.
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9
