NAME

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

SYNOPSIS

/sys/conf/SYSTEM:
NBRbr_drives# EATON 1537/1711, EATON 1538A, B, C, D
 /etc/dtab:
#NameUnit#AddrVectorBrHandler(s) # Comments
br?1767102545brintr# 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 therefore 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 sector).  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:

1538A partitions:
disk length     cylscomments
br?a  18260  0  - 1651538A 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     cylscomments
br?a  18400  0  - 1141538B 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     cylscomments
br?a  18392  0  - 431538C 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     cylscomments
br?a  18240  0  - 291538D 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/MAKEDEVscript to create special files
/dev/MAKEDEV.localscript to localize special files

SEE ALSO

ra(4), ram(4), rk(4), rl(4), rx(4), si(4), xp(4), dtab(5), autoconfig(8)

DIAGNOSTICS

br%d%c: hard error sn%d cs2=%b ds=%b er=%b.  An unrecoverable 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.

2nd Berkeley Distribution  —  August 20, 1988