mirror of https://github.com/mkerrisk/man-pages
138 lines
3.7 KiB
Groff
138 lines
3.7 KiB
Groff
.\" sd.4
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.\" Copyright 1992 Rickard E. Faith (faith@cs.unc.edu)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH SD 4 2017-09-15 "Linux" "Linux Programmer's Manual"
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.SH NAME
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sd \- driver for SCSI disk drives
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.SH SYNOPSIS
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.nf
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.BR "#include <linux/hdreg.h> " "/* for HDIO_GETGEO */"
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.BR "#include <linux/fs.h> " "/* for BLKGETSIZE and BLKRRPART */"
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.fi
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.SH CONFIGURATION
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The block device name has the following form:
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.BI sd lp,
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where
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.I l
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is a letter denoting the physical drive, and
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.I p
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is a number denoting the partition on that physical drive.
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Often, the partition number,
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.IR p ,
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will be left off when the device corresponds to the whole drive.
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.PP
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SCSI disks have a major device number of 8, and a minor device number of
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the form (16 *
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.IR drive_number ") + " partition_number ,
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where
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.I drive_number
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is the number of the physical drive in order of detection, and
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.I partition_number
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is as follows:
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.IP +3
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partition 0 is the whole drive
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.IP
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partitions 1\(en4 are the DOS "primary" partitions
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.IP
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partitions 5\(en8 are the DOS "extended" (or "logical") partitions
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.PP
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For example,
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.I /dev/sda
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will have major 8, minor 0, and will refer to all of the first SCSI drive
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in the system; and
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.I /dev/sdb3
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will have major 8, minor 19, and will refer to the third DOS "primary"
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partition on the second SCSI drive in the system.
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.PP
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At this time, only block devices are provided.
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Raw devices have not yet been implemented.
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.SH DESCRIPTION
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The following
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.IR ioctl s
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are provided:
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.TP
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.B HDIO_GETGEO
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Returns the BIOS disk parameters in the following structure:
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.PP
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.in +4n
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.EX
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struct hd_geometry {
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unsigned char heads;
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unsigned char sectors;
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unsigned short cylinders;
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unsigned long start;
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};
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.EE
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.in
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.IP
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A pointer to this structure is passed as the
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.BR ioctl (2)
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parameter.
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.IP
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The information returned in the parameter is the disk geometry of the drive
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.I "as understood by DOS!"
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This geometry is
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.I not
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the physical geometry of the drive.
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It is used when constructing the
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drive's partition table, however, and is needed for convenient operation
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of
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.BR fdisk (1),
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.BR efdisk (1),
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and
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.BR lilo (1).
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If the geometry information is not available, zero will be returned for all
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of the parameters.
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.TP
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.B BLKGETSIZE
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Returns the device size in sectors.
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The
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.BR ioctl (2)
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parameter should be a pointer to a
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.IR long .
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.TP
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.B BLKRRPART
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Forces a reread of the SCSI disk partition tables.
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No parameter is needed.
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.IP
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The SCSI
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.BR ioctl (2)
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operations are also supported.
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If the
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.BR ioctl (2)
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parameter is required, and it is NULL, then
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.BR ioctl (2)
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fails with the error
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.BR EINVAL .
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.SH FILES
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.TP
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.I /dev/sd[a\-h]
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the whole device
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.TP
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.I /dev/sd[a\-h][0\-8]
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individual block partitions
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.\".SH SEE ALSO
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.\".BR scsi (4)
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