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



NAME
       sd - Driver for SCSI Disk Drives

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

CONFIGURATION
       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  corre-
       sponds 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
       The following ioctls are provided:

       HDIO_GETGEO
              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) parameter.

              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 avail-
              able, zero will be returned for all of the parameters.

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

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

              The  scsi(4)  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
       /dev/sd[a-h]: the whole device
       /dev/sd[a-h][0-8]: individual block partitions

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                                                      1992-12-17                                                      SD(4)