2.9BSD/usr/man/man4/rf.4

.TH RF 4 
.UC
.SH NAME
rf \- RF11/RS11 fixed-head disk
.SH DESCRIPTION
This file refers to the
concatenation of all RS-11 disks.
.PP
Each disk contains 1024 512-byte blocks.
The length of the combined RF file is
1024\(mu(minor+1) blocks.
That is, minor device zero
is taken to be
1024 blocks long;
minor device one is 2048 blocks long,
etc.
.PP
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 name of the raw files conventionally begin with an extra `r.'
.PP
In raw I/O counts should be a multiple of 512 bytes
(a disk sector).
Likewise
.IR lseek (2)
calls should specify a multiple of 512 bytes.
.SH FILES
.ta 2i
/dev/rf[0-7]	block files
.br
/dev/rrf[0-7]	raw files
.SH "SEE ALSO"
dvhp(4), hk(4), hp(4), hs(4), ml(4), rk(4), rl(4), rm(4), rp(4), rx2(4), xp(4)
.SH DIAGNOSTICS
\fBrf%d: hard error bn %d cs=%b dae=%b\fP.  An unrecoverable
error occured during transfer of the specified sector of the specified
disk partition.  The contents of the two error registers are also printed
in octal and symbolically with bits decoded.
The error was either unrecoverable, or a large number of retry attempts
could not recover the error.
.PP
\fBrf%d: write locked\fP.  The write protect switch was set on the drive
when a write was attempted.  The write operation is not recoverable.
.SH BUGS
In raw I/O
.I read
and
.IR write (2)
truncate file offsets to 512-byte block boundaries,
and
.I write
scribbles on the tail of incomplete blocks.
Thus,
in programs that are likely to access raw devices,
.I read, write
and
.IR lseek (2)
should always deal in 512-byte multiples.
.PP
DEC-standard error logging should be supported.