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

NAME
     sd - machine-independent SCSI disk driver

SYNOPSIS
     options SCSI
     disk sd0 at tg?

DESCRIPTION
     The sd driver for disks on the Small Computer System Interface (ANSI
     X3.131-1992) bus is a machine-independent generic device which employs
     machine-dependent drivers for individual host adapters to read and write
     data blocks.  The sd driver takes care of queuing requests and sorting
     them by cylinder address on each logical unit; generating the correct
     read and write SCSI Command Descriptor Blocks, along with inquiry, test
     unit ready and other common operations; reading and writing disk labels;
     classifying SCSI errors and gathering extended error information; and
     probing for logical units on SCSI targets and identifying their type.
     The driver also supports an interface for raw SCSI commands; see
     scsicmd(8).

FILES
     /dev/sd[0-6][a-h]  SCSI disk devices

SEE ALSO
     scsicmd(8),  st(4)

HISTORY
     This driver was written by Chris Torek for SPARC BSD, and was contributed
     by his employer, the Lawrence Berkeley Laboratories.

BUGS
     Errors returned by the driver consist of a sense key and possible addi-
     tional sense information.  The sense key is printed in English but the
     myriad ASC and ASCQ values must be decoded using the -a option of
     scsicmd.

     Standalone boot blocks and 14-sector bootstraps are necessarily dependent
     on the host adapter.  There are no sdboot or bootsd files; these are in-
     stead named after individual host adapters.

     All zone recorded disks are treated as having a uniform geometry.  This
     means that rotational optimizations may be correct only on some subset of
     the disk cylinders, if any.

BSDI BSD/386                    March 27, 1993                               1