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

NAME         top

       sd - driver for SCSI disk drives

SYNOPSIS         top

       #include <linux/hdreg.h>        /* for HDIO_GETGEO */
       #include <linux/fs.h>           /* for BLKGETSIZE and BLKRRPART */


       The block device name has the following form: sdlp, where l is a
       letter denoting the physical drive, and p is a number denoting the
       partition on that physical drive.  Often, the partition number, p,
       will be left off when the device corresponds to the whole drive.

       SCSI disks have a major device number of 8, and a minor device number
       of the form (16 * drive_number) + partition_number, where
       drive_number is the number of the physical drive in order of
       detection, and partition_number is as follows:

       partition 0 is the whole drive
       partitions 1-4 are the DOS "primary" partitions
       partitions 5-8 are the DOS "extended" (or "logical") partitions

       For example, /dev/sda will have major 8, minor 0, and will refer to
       all of the first SCSI drive in the system; and /dev/sdb3 will have
       major 8, minor 19, and will refer to the third DOS "primary"
       partition on the second SCSI drive in the system.

       At this time, only block devices are provided.  Raw devices have not
       yet been implemented.

DESCRIPTION         top

       The following ioctls are provided:

              Returns the BIOS disk parameters in the following structure:

                  struct hd_geometry {
                      unsigned char  heads;
                      unsigned char  sectors;
                      unsigned short cylinders;
                      unsigned long  start;

              A pointer to this structure is passed as the ioctl(2)

              The information returned in the parameter is the disk geometry
              of the drive as understood by DOS!  This geometry is not the
              physical geometry of the drive.  It is used when constructing
              the drive's partition table, however, and is needed for
              convenient operation of fdisk(1), efdisk(1), and lilo(1).  If
              the geometry information is not available, zero will be
              returned for all of the parameters.

              Returns the device size in sectors.  The ioctl(2) parameter
              should be a pointer to a long.

              Forces a reread of the SCSI disk partition tables.  No
              parameter is needed.

              The SCSI ioctl(2) operations are also supported.  If the
              ioctl(2) parameter is required, and it is NULL, then ioctl(2)
              will fail with the error EINVAL.

FILES         top

       /dev/sd[a-h]: the whole device
       /dev/sd[a-h][0-8]: individual block partitions

COLOPHON         top

       This page is part of release 4.08 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

Linux                            2012-05-03                            SD(4)