sd — Driver for SCSI Disk Drives
#include <linux/hdreg.h> /* for HDIO_GETGEO */ #include <linux/fs.h> /* for BLKGETSIZE and BLKRRPART */
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.
The following ioctls are
provided:
HDIO_GETGEOReturns 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
notthe 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.
BLKGETSIZEReturns the device size in sectors. The ioctl(2) parameter
should be a pointer to a long.
BLKRRPARTForces a re-read of the SCSI disk partition tables. No parameter is needed.
The scsi(4) 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.