sd(7)                  DEVICES AND MODULES                  sd(7)



NAME
     sd - SCSI disk device driver

SYNOPSIS
     /dev/sd[00-07]
     /dev/rsd[00-07]

DESCRIPTION
     sd is the SCSI disk device driver.  This driver  supports  3
     types of SCSI drives:

          Sealed (Winchester) hard disk drives

          Magneto-optical drives

          CD-ROM drives

     sd recognizes direct access drives (SCSI device  type  0x00)
     and read-only direct access devices (SCSI device type 0x05).

     The SCSI disk subsystem may consist of up to 8 partitions in
     different  disk  sizes;  for  example,  286MB or 640MB.  The
     files /dev/dsk/c0d0s0 ... /dev/dsk/c0d0s7 refer to different
     partitions of the first SCSI disk.

     The /dev/dsk files  provide  access  to  the  disk  via  the
     system's  normal  buffering  mechanism.  There is also a raw
     (character) interface which provides for direct transfer  of
     a  specified number of bytes between the disk and a location
     in the user's address space.  The  names  of  the  raw  disk
     files  are  in  directory  /dev/rdsk and are the same as the
     corresponding /dev/dsk files.  In raw I/O the read or  write
     must  begin  on  a  word boundary; transfer counts can be as
     small as a single byte.

     Disk device file names are in the following format:

                          /dev/{r}dsk/c#d#s#

     where r indicates a raw interface to the disk, the c#  indi-
     cates   the  controller  number,  d#  indicates  the  device
     attached to the controller (unit number)  and  s#  indicates
     the partition number of the disk.

     For a controller with more than one SCSI bus, the controller
     numbers are defined as follows:

          c0 - c7         first  SCSI bus
          c8 - c15        second SCSI bus
          ...

     The unit number of the internal SCSI hard disk is usually  0



                                                                1

sd(7)                  DEVICES AND MODULES                  sd(7)



     (d0).

     The first partition of the root disk is usually used for the
     root  file  system. The second partition of the root disk is
     used for swap space.

     Partition number 2  (/dev/dsk/c#d0s2,  /dev/rdsk/c#d0s2)  in
     the disk partition table is used for the entire disk.

SUPPORTED DEVICES
     The  devices  supported  by  the  driver  are  described  in
     /usr/include/io/sddefs.h.   At  boot  time, the driver reads
     the volume table of contents (VTOC) and uses  this  informa-
     tion  to  determine  the  sizes and offsets of the different
     partitions on a disk.

     For those disks without a valid label, the  device  informa-
     tion  table,  sddevinfo, in /usr/include/io/sddefs.h is used
     to calculate capacity and partition sizes.  Thus, it is very
     important that a valid VTOC exist on the disk.

     New devices can be supported by adding device information to
     this  table.   However,  avoid  changing data recorded in an
     existing device information table.

     Refer to /usr/include/io/sdreg.h for the format of a  device
     information table.

     Devices with removeable media are automatically spun  up  or
     down  at  open and close, respectively.  While the device is
     open, attempts to eject the media are not allowed.

IOCTLS
     sd ioctls are located in the following files:
     /usr/include/io/dkio.h
     /usr/include/io/sdreg.h
     /usr/include/io/scu.h
     /usr/include/io/cdctl.h
     /usr/include/io/diskinfo.h
     /usr/include/io/disklabel.h
     /usr/include/io/dk.h

FILES
     /dev/dsk/c#d0s#
     /dev/rdsk/c#d0s#
     /usr/include/io/sddefs.h    disk device information file
     /usr/include/io/sdreg.h     ioctl command/structure  defini-
     tion
     /usr/include/io/dkio.h      ioctl command/structure  defini-
     tion
     /usr/include/io/scu.h       ioctl command/structure  defini-
     tion



                                                                2

sd(7)                  DEVICES AND MODULES                  sd(7)



     /usr/include/io/cdctl.h     ioctl command/structure  defini-
     tion for CD-ROM

SEE ALSO
     format(1M)      media format command
     fmthard(1M)     disk label and partition command
     prtvtoc(1M)     print label command
     newfs(1M)       front end for mkfs
     /etc/disktab    disk partition table














































                                                                3