sd(4) - man - phpman

SD(4)                                 Linux Programmer's Manual                                SD(4)



NAME
       sd - driver for SCSI disk drives

SYNOPSIS
       #include <linux/hdreg.h>        /* for HDIO_GETGEO */
       #include <linux/fs.h>           /* for BLKGETSIZE and BLKRRPART */

CONFIGURATION
       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:

       +3     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.

DESCRIPTION
       The following ioctls are provided:

       HDIO_GETGEO
              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 under‐
              stood 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 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.

       BLKGETSIZE
              Returns  the  device size in sectors.  The ioctl(2) parameter should be a pointer to a
              long.

       BLKRRPART
              Forces a reread of the SCSI disk partition tables.  No parameter is needed.

              The SCSI ioctl(2) operations are also supported.  If the  ioctl(2)  parameter  is  re‐
              quired, and it is NULL, then ioctl(2) fails with the error EINVAL.

FILES
       /dev/sd[a-h]
              the whole device

       /dev/sd[a-h][0-8]
              individual block partitions

COLOPHON
       This  page  is  part  of  release  5.10 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of this page, can be  found
       at https://www.kernel.org/doc/man-pages/.



Linux                                        2017-09-15                                        SD(4)