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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 */

CONFIG
       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 parti-
       tion_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 conve-
              nient 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 re-read of the SCSI disk partition tables.  No parame-
              ter is needed.

              The scsi(4) ioctls are also supported.  If the ioctl(2)  parame-
              ter  is required, and it is NULL, then ioctl() will return -EIN-
              VAL.

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



                                  1992-12-17                             SD(4)