sd



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.

     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 ALSO

     intro(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 5.4                      June 5, 2011                      OpenBSD 5.4

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