blob: b80396c476e9e105a5777753c8789d9384e3d5b9 [file] [log] [blame]
.\" sd.4
.\" Copyright 1992 Rickard E. Faith (
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.TH SD 4 2017-09-15 "Linux" "Linux Programmer's Manual"
sd \- driver for SCSI disk drives
.BR "#include <linux/hdreg.h> " "/* for HDIO_GETGEO */"
.BR "#include <linux/fs.h> " "/* for BLKGETSIZE and BLKRRPART */"
The block device name has the following form:
.BI sd lp,
.I l
is a letter denoting the physical drive, and
.I p
is a number denoting the partition on that physical drive.
Often, the partition number,
.IR 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 *
.IR drive_number ") + " partition_number ,
.I drive_number
is the number of the physical drive in order of detection, and
.I partition_number
is as follows:
.IP +3
partition 0 is the whole drive
partitions 1\(en4 are the DOS "primary" partitions
partitions 5\(en8 are the DOS "extended" (or "logical") partitions
For example,
.I /dev/sda
will have major 8, minor 0, and will refer to all of the first SCSI drive
in the system; and
.I /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.
The following
.IR ioctl s
are provided:
Returns the BIOS disk parameters in the following structure:
.in +4n
struct hd_geometry {
unsigned char heads;
unsigned char sectors;
unsigned short cylinders;
unsigned long start;
A pointer to this structure is passed as the
.BR ioctl (2)
The information returned in the parameter is the disk geometry of the drive
.I "as understood by DOS!"
This geometry is
.I not
the physical geometry of the drive.
It is used when constructing the
drive's partition table, however, and is needed for convenient operation
.BR fdisk (1),
.BR efdisk (1),
.BR lilo (1).
If the geometry information is not available, zero will be returned for all
of the parameters.
Returns the device size in sectors.
.BR ioctl (2)
parameter should be a pointer to a
.IR long .
Forces a reread of the SCSI disk partition tables.
No parameter is needed.
.BR ioctl (2)
operations are also supported.
If the
.BR ioctl (2)
parameter is required, and it is NULL, then
.BR ioctl (2)
fails with the error
.I /dev/sd[a\-h]
the whole device
.I /dev/sd[a\-h][0\-8]
individual block partitions
.\".BR scsi (4)