.TH RL 4
.UC
.SH NAME
rl \- RL-11/RL01, RL02 moving-head disk
.SH DESCRIPTION
.I Rl?
refers to an entire disk as a single sequentially addressed
file.  The RL01 drives are each 10240 blocks long and the RL02
drives are 20480 blocks long.
The standard device names begin with ``rl'' followed by
the drive number.
.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 names of the raw files
conventionally begin with an extra `r.'
.PP
In raw I/O counts should be a multiple of 512 bytes.
Likewise
.I lseek
calls should specify a multiple of 512 bytes.
.SH FILES
.ta 2i
/dev/rl[0-3]	block files
.br
/dev/rrl[0-3]	raw files
.SH "SEE ALSO"
dvhp(4), hk(4), hp(4), hs(4), ml(4), rf(4), rk(4), rm(4), rp(4), rx2(4), xp(4)
.SH DIAGNOSTICS
\fBrl%d: hard error bn %d cs=%b da=%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
\fBrl%d: hard error sn%d mp=%b da=%b\fP.  An unrecoverable drive
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
\fBrl%d: write locked\fP.  The write protect switch was set on the drive
when a write was attempted.  The write operation is not recoverable.
.PP
\fBrl%d: can't get status\fP.  A ``get status'' command on the specified
drive failed.  The error is unrecoverable.
.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.
.PP
A program to analyze the logged error information (even in its
present reduced form) is needed.