DSKD(7)             RISC/os Reference Manual              DSKD(7)



NAME
     dksd - general SCSI disk interface.

SYNOPSIS
     VECTOR: module=sha vector=0xD ipl=2 unit=6 base=060

DESCRIPTION
     This is a general SCSI disk driver and should work with most
     drives that have embedded controllers.  Files with minor
     device numbers 0 through 15 refer to various portions of
     target0, lun0; minor devices 16 through 31 refer to target0,
     lun1, etc.  The driver uses the standard System V naming
     convention.

     The block files access the disk via the system's normal
     buffering mechanism and may be read and written without
     regard to physical disk records.  There is also a `raw'
     interface that provides for direct transmission between the
     disk and the user's read or write buffer.  A single read or
     write call results in exactly one I/O operation and there-
     fore raw I/O is considerably more efficient when many words
     are transmitted.  The names of the raw files conventionally
     begin with an extra `r.'

     In raw I/O, buffers should be page aligned for best perfor-
     mance and I/O counts should be a multiple of 512 bytes (a
     disk sector).  Likewise seek calls should specify a multiple
     of 512 bytes.

     Disk volumes on ISI computers systems contain a volume
     header that describes the contents of the disk and parame-
     ters of the physical disk drive.  The volume header is a
     block located at the beginning of all disk media.  It con-
     tains information about physical device parameters and logi-
     cal partitions.  Refer to dvh(4) for details on the disk
     volume header format.  Volume headers are created by for-
     matters and, may be manipulated by dvhtool(1M) via the spe-
     cial raw device ``rsd?vh''.  Another special raw device
     exists, ``rsd?vol'' for use by formatters to access the
     entire disk volume.

DISK SUPPORT
     This driver configures the drive type of each drive, during
     initialization, based on the information in the volume
     header for the particular device.  The partition table is
     also contained in the volume header.

     The ``sds?d0s0'' partition is normally used for the root
     file system, and the ``sd?d0s1'' partition as a paging area.
     The ``sds?d0s2'' partition maps all the UNIX file system
     partitions, while ``sd?vol'' maps the entire disk.




                        Printed 11/19/92                   Page 1

DSKD(7)             RISC/os Reference Manual              DSKD(7)



FILES
     /dev/sds[0-4]d0s[0-7]    block files

     /dev/rsds[0-4]d0s[0-7]   raw files

     /dev/sd[0-4]vh           volume header partition

     /dev/sd[0-4]vol          entire volume partition

SEE ALSO
     dvhtool(1M)
     dvh(4) in the Programmer's Reference Manual.

DIAGNOSTICS
     sense failed: %s: scsi %b
          An error occurred during a sense command.  The sense
          commands are normally issued only when some other com-
          mand like a read or write failed.

     no more retries
          When an error has occurred the driver will retry the
          command up to 3 times.

ERRORS
     The logged error information should be saved somewhere in
     the volume directory.

     A program to analyze the logged error information (even in
     its present reduced form) is needed.


























 Page 2                 Printed 11/19/92