man4/sd.4

   1 .\" sd.4
   2 .\" Copyright 1992 Rickard E. Faith (faith@cs.unc.edu)
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .\"
   6 .TH sd 4 (date) "Linux man-pages (unreleased)"
   7 .SH NAME
   8 sd \- driver for SCSI disk drives
   9 .SH SYNOPSIS
  10 .nf
  11 .BR "#include <linux/hdreg.h>        " "/* for HDIO_GETGEO */"
  12 .BR "#include <linux/fs.h>           " "/* for BLKGETSIZE and BLKRRPART */"
  13 .fi
  14 .SH CONFIGURATION
  15 The block device name has the following form:
  16 .BI sd lp,
  17 where
  18 .I l
  19 is a letter denoting the physical drive, and
  20 .I p
  21 is a number denoting the partition on that physical drive.
  22 Often, the partition number,
  23 .IR p ,
  24 will be left off when the device corresponds to the whole drive.
  25 .PP
  26 SCSI disks have a major device number of 8, and a minor device number of
  27 the form (16 *
  28 .IR drive_number ") + " partition_number ,
  29 where
  30 .I drive_number
  31 is the number of the physical drive in order of detection, and
  32 .I partition_number
  33 is as follows:
  34 .IP \(bu 3
  35 partition 0 is the whole drive
  36 .IP \(bu
  37 partitions 1\(en4 are the DOS "primary" partitions
  38 .IP \(bu
  39 partitions 5\(en8 are the DOS "extended" (or "logical") partitions
  40 .PP
  41 For example,
  42 .I /dev/sda
  43 will have major 8, minor 0, and will refer to all of the first SCSI drive
  44 in the system; and
  45 .I /dev/sdb3
  46 will have major 8, minor 19, and will refer to the third DOS "primary"
  47 partition on the second SCSI drive in the system.
  48 .PP
  49 At this time, only block devices are provided.
  50 Raw devices have not yet been implemented.
  51 .SH DESCRIPTION
  52 The following
  53 .IR ioctl s
  54 are provided:
  55 .TP
  56 .B HDIO_GETGEO
  57 Returns the BIOS disk parameters in the following structure:
  58 .PP
  59 .in +4n
  60 .EX
  61 struct hd_geometry {
  62     unsigned char  heads;
  63     unsigned char  sectors;
  64     unsigned short cylinders;
  65     unsigned long  start;
  66 };
  67 .EE
  68 .in
  69 .IP
  70 A pointer to this structure is passed as the
  71 .BR ioctl (2)
  72 parameter.
  73 .IP
  74 The information returned in the parameter is the disk geometry of the drive
  75 .I "as understood by DOS!"
  76 This geometry is
  77 .I not
  78 the physical geometry of the drive.
  79 It is used when constructing the
  80 drive's partition table, however, and is needed for convenient operation
  81 of
  82 .BR fdisk (1),
  83 .BR efdisk (1),
  84 and
  85 .BR lilo (1).
  86 If the geometry information is not available, zero will be returned for all
  87 of the parameters.
  88 .TP
  89 .B BLKGETSIZE
  90 Returns the device size in sectors.
  91 The
  92 .BR ioctl (2)
  93 parameter should be a pointer to a
  94 .IR long .
  95 .TP
  96 .B BLKRRPART
  97 Forces a reread of the SCSI disk partition tables.
  98 No parameter is needed.
  99 .IP
 100 The SCSI
 101 .BR ioctl (2)
 102 operations are also supported.
 103 If the
 104 .BR ioctl (2)
 105 parameter is required, and it is NULL, then
 106 .BR ioctl (2)
 107 fails with the error
 108 .BR EINVAL .
 109 .SH FILES
 110 .TP
 111 .I /dev/sd[a\-h]
 112 the whole device
 113 .TP
 114 .I /dev/sd[a\-h][0\-8]
 115 individual block partitions
 116 .\".SH SEE ALSO
 117 .\".BR scsi (4)