2.11BSD#431 - /usr/man/cat4/br.0

BR(4)		    UNIX Programmer's Manual		    BR(4)


NAME
     br - EATON BR1537/BR1711 1538[A,B,C,D] moving head disk

SYNOPSIS
     /sys/conf/SYSTEM:
	  NBR  br_drives # EATON 1537/1711, EATON 1538A, B, C, D

     /etc/dtab:
	  #Name Unit# Addr   Vector Br Handler(s)      # Comments
     br   ?	176710	     254    5  brintr	       # Eaton 1537/8

     major device number(s):
	  raw: 20
	  block: 11
     minor device encoding:
	  bits 0007 specify partition of BR drive
	  bits 0070 specify BR drive

DESCRIPTION
     Files with minor device numbers 0 through 7 refer to various
     portions of drive 0; minor devices 8 through 15 refer to
     drive 1, etc.  There are four drive types supported by the
     Eaton BR1537 and BR1711 controllers, these are the 1538A (50
     Mb), 1538B (80 Mb), 1538C (200 Mb) and 1538D (300 Mb).
     Capacities are unformatted megabytes.  The standard device
     names begin with ``br'' followed by the drive number and
     then a letter a-h for partitions 0-7 respectively.  The
     character ? stands here for a drive number in the range 0-7.

     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 which 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 the buffer must begin on a word (even) boundary,
     and counts should be a multiple of 512 bytes (a disk sec-
     tor).  Likewise seek calls should specify a multiple of 512
     bytes.

DISK SUPPORT
     The size (in sectors) of the pseudo-disks on each drive are
     as follows:


Printed 11/26/99	 August 20, 1988			1


BR(4)		    UNIX Programmer's Manual		    BR(4)


     1538A partitions:
	  disk	 length      cyls	   comments
	  br?a	  18260   0  - 165	   1538A has 22 sec/trk, 5 trk/cyl
	  br?b	  12210  166 - 276
	  br?c	  59180  277 - 814
	  br?d	  unused
	  br?e	  unused
	  br?f	  unused
	  br?g	  unused
	  br?h	  89650   0  - 814

     1538B partitions:
	  disk	 length      cyls	   comments
	  br?a	  18400   0  - 114	   1538B has 32 sec/trk, 5 trk/cyl
	  br?b	  12320  115 - 190
	  br?c	  99840  191 - 814
	  br?d	  unused
	  br?e	  unused
	  br?f	  unused
	  br?g	  unused
	  br?h	  99840   0  - 814

     1538C partitions:
	  disk	 length      cyls	   comments
	  br?a	  18392   0  - 43	   1538C has 22 sec/trk, 19 trk/cyl
	  br?b	  12122  44  - 72
	  br?c	 231990  73 - 627
	  br?d	  78166 628 - 814
	  br?e	  unused
	  br?f	  unused
	  br?g	  unused
	  br?h	 340670   0  - 814

     1538D partitions:
	  disk	 length      cyls	   comments
	  br?a	  18240   0  - 29	   1538D has 32 sec/trk, 19 trk/cyl
	  br?b	  12160  30  - 49
	  br?c	 232256  50 - 431
	  br?d	 232256 432 - 813
	  br?e	  unused
	  br?f	  unused
	  br?g	  unused
	  br?h	 495520   0  - 814

FILES
     /dev/br[0-7][a-h]	 block files
     /dev/rbr[0-7][a-h]  raw files
     /dev/MAKEDEV	 script to create special files
     /dev/MAKEDEV.local  script to localize special files

SEE ALSO
     ra(4), ram(4), rk(4), rl(4), rx(4), si(4), xp(4), dtab(5),


Printed 11/26/99	 August 20, 1988			2


BR(4)		    UNIX Programmer's Manual		    BR(4)


     autoconfig(8)

DIAGNOSTICS
     br%d%c: hard error sn%d cs2=%b ds=%b er=%b.  An unrecover-
     able error occurred during transfer of the specified sector
     of the specified disk partition.  The contents of the cs2,
     ds and er registers are printed in octal and symbolically
     with bits decoded.  The error was either unrecoverable, or a
     large number of retry attempts (including offset positioning
     and drive recalibration) could not recover the error.

BUGS
     In raw I/O read and write(2) truncate file offsets to 512-
     byte block boundaries, and write scribbles on the tail of
     incomplete blocks.  Thus, in programs that are likely to
     access raw devices, read, write and lseek(2) should always
     deal in 512-byte multiples.

     DEC-standard error logging should be supported.

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

     The partition tables for the file systems should be read off
     of each pack, as they are never quite what any single
     installation would prefer, and this would make packs more
     portable.

     Only the 1538D (300Mb) disk has been used with this driver,
     the disktab(5) file and newfs(8) program only know about the
     1538D.


Printed 11/26/99	 August 20, 1988			3