hd(7)                                                                 hd(7)


   NAME
         hd - hard disk interface

   DESCRIPTION
         hd provides the interface to all types of SCSI hard disk units, and
         uses the scsi(7) interface to communicate with the SCSI hardware.

         The binary representation of the minor device number is encoded as
         tttdddmpppp where ttt is the SCSI target id and ddd is the SCSI
         logical unit (drive) number and pppp is the partition number on that
         drive.  The f partition is reserved to access the whole physical
         disk.  This can be useful when, for example, it is required to make a
         copy of an entire removable disk cartridge.

         The following extra fields are implemented in the pdsector structure
         (which is defined in /usr/include/sys/vtoc.h).

         #define interleave      devsp[0]
         #define wholedisksize   devsp[1]

         The meanings of these fields are as follows:

         wholedisksize
               The total physical disk size (in 512-byte blocks).

         interleave
               Used during SCSI formatting to specify the hardware interleave.

         Both block and character (raw) interfaces are provided.  The block
         interface accesses the disk via the system's normal buffering
         mechanism and may be read or written without regard to physical disk
         records.

         The raw interface provides for direct transmission between the disk
         and the user's data area; thus I/O is considerably more efficient
         when large amounts of data are to be transferred.  However, seeks are
         truncated to 512-byte block boundaries and attempts to transfer data
         in quantities that are not in multiples of 512 bytes will fail,
         returning an error condition.

         The device tables, i.e. the pdsector and vtoc are obtained upon
         opening any disk partition except the last, which is reserved as the
         whole physical disk. All disk administration tools should therefore
         avoid using the f partition, as it will not load the required disk
         tables.  Partinit must use the f partition.

   FILES
         /dev/dsk/cXdYsZ  Block interface for SCSI target X, logical unit Y,
                          partition (slice) Z.




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   hd(7)                                                                 hd(7)


         /dev/dsk/cXdYsf  Block whole disk interface for physical drive on
                          SCSI target X, logical unit Y.

         /dev/rdsk/cXdYsZ Raw interface for SCSI target X, logical unit Y,
                          partition Z.

         /dev/rdsk/cXdYsf Raw whole disk interface for physical drive on SCSI
                          target X, logical unit Y.

   SEE ALSO
         disk(7), scsi(7).










































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