MirBSD manpage: sd(4)

SD(4)                      BSD Programmer's Manual                       SD(4)


     sd - SCSI disk driver


     sd* at scsibus? target ? lun ?
     #sd0 at scsibus0 target 3 lun 0 (fixed-configuration example)


     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 config-

     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.


     On many systems disklabel(8) is used to partition the drive into filesys-
     tems. On some systems the OpenBSD portion of the disk resides within a
     native partition, and another program is used to create the OpenBSD por-

     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


     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 in-
                 formation 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 car-
                 tridge previously locked. Used to prevent user and software
                 eject while the media is in use.

     DIOCEJECT   Eject the media cartridge from a removable device.

     In addition, the scsi(4) general ioctl() commands may be used with the sd
     driver, but only against the 'c' (whole disk) partition.


     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.


     /dev/sdup      block mode SCSI disk unit u, partition p
     /dev/rsdup     raw mode SCSI disk unit u, partition p




     intro(4), scsi(4), wd(4), disklabel(5), disklabel(8), fdisk(8)


     The sd driver was originally written for Mach 2.5, and was ported to
     FreeBSD by Julian Elischer. It was later ported to OpenBSD.

MirBSD #10-current             January 18, 1996                              1

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