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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 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
              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.

       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

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