Computer Science
SD(4) Linux Programmer's Manual SD(4)
NAME
sd - Driver for SCSI Disk Drives
SYNOPSIS
#include <linux/hdreg.h>
CONFIG
The block device name has the following form: sdlp, where
l is a letter denoting the physical drive, and p is a num-
ber 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) + parti-
tion_number, where drive_number is the number of the phys-
ical 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") par-
titions
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 ioctl's are provided:
HDIO_REQ
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 conve-
nient 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 re-read of the SCSI disk partition tables.
No parameter is needed.
The scsi(4) ioctls are also supported. If the
ioctl(2) parameter is required, and it is NULL,
then ioctl(2) will return -EINVAL.
FILES
/dev/sd[a-h]: the whole device
/dev/sd[a-h][0-8]: individual block partitions
SEE ALSO
scsi(4)
Thu Dec 17 10:15:53 1992 1
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