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

NAME
       sd - driver for SCSI disk drives

SYNOPSIS
       #include         /* for HDIO_GETGEO */
       #include            /* for BLKGETSIZE and BLKRRPART */

CONFIGURATION
       The block device name has the following form: sdlp, where l is a letter denoting the phys‐
       ical 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
       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 con‐
              venient 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.

       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 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 4.04 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 http://www.kernel.org/doc/man-pages/.

Linux                                       2012-05-03                                      SD(4)

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