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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 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  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 4.09 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
   https://www.kernel.org/doc/man-pages/.



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