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

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.TH XP 4
.UC
.SH NAME
xp \- RP04, RP05, RP06, RM02, RM03, RM05, Diva moving-head disk
.SH DESCRIPTION
The
.I xp
driver is designed to be used when more than one class of disks
is present on one or more controllers of the SMD type.
The drives are numbered from 0 to \fIn\fP on controller 0,
from \fIn\fP+1 to \fIm\fP on controller 1, etc.
The drives may have different or nonstandard geometry
if the driver's data structures are initialized,
allowing use of drives such as the Fujitsu 160 Mb.
.PP
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.
The standard device names begin with ``xp'' 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.
.PP
The origin and size of the partitions (in 512-byte sectors) on each drive are
as follows:
.PP
.nf
.ta .5i +\w'000000    'u +\w'000000    'u +\w'000000    'u +\w'000000    'u
RP04/RP05/RP06 partitions:
	disk	start	length	cyls	function on drive 0
	xp?a	0	9614	0-22	/
	xp?b	9614	8779	23-43	swap
	xp?c	18392	153406	44-410	/usr (RP04, RP05)
	xp?d	171798	168872	411-814	rest of RP06
	xp?e	18392	322278	44-814	alternate, RP06
	xp?g	0	171798	0-410	whole RP04/5
	xp?h	0	322278	0-814	whole RP06
.PP
.nf
RM02/RM03 partitions:
	disk	start	length	cyls	function on drive 0
	xp?a	0	4800	0-29	/
	xp?b	4800	4800	30-59	swap
	xp?c	9600	122080	60-822	/usr
	xp?d	9600	62720	60-451	alternate
	xp?e	72320	59360	452-822	alternate
	xp?h	0	131680	0-822	whole pack
.PP
.nf
RM05 partitions:
	disk	start	length	cyls	function on drive 0
	xp?a	0	9120	  0-14	/
	xp?b	9120	9120	 15-29	swap
	xp?c	18240	234080	 30-414	
	xp?d	252320	248064	415-822	
	xp?e	18240	164160	 30-299	/usr
	xp?f	182400	152000	300-549	
	xp?g	334400	165376	550-822	
	xp?h	0	500384	  0-822	whole pack
.PP
.nf
Diva Comp V / Ampex 9300 partitions:
	disk	start	length	cyls	function on drive 0
	xp?a	0	9405	0-14	/
	xp?b	9405	9405	15-29	swap
	xp?c	18810	241395	30-414	
	xp?d	260205	250800	415-814	
	xp?e	18810	169290	30-299	/usr
	xp?f	188100	156750	300-549	
	xp?g	313500	165528	550-814	
	xp?h	0	511005	0-814	whole pack
.DT
.fi
.PP
Special files should only be created for the
partitions that are actually used,
as the overlap in these addresses could lead to confusion otherwise.
.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 (a disk sector).
Likewise
.I lseek
calls should specify a multiple of 512 bytes.
.SH FILES
.ta 2i
/dev/xp[0-7][a-h]	block files
.br
/dev/rxp[0-7][a-h]	raw files
.SH SEE ALSO
dvhp(4), hk(4), hp(4), hs(4), ml(4), rf(4), rk(4), rl(4), rm(4), rp(4), rx2(4)
.SH DIAGNOSTICS
\fBxp%d%c: hard error bn %d cs2=%b er1=%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
(including offset positioning and drive recalibration) could not
recover the error.
.PP
\fBxp%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
\fBxp%d%c: soft ecc bn %d\fP.  A recoverable ECC error occurred on the
specified sector of the specified disk partition.  This happens normally
a few times a week.  If it happens more frequently than
this the sectors where the errors are occuring should be checked to see
if certain cylinders on the pack, spots on the carriage of the drive
or heads are indicated.
.PP
\fBxp%d: unknown device type 0%o\fP.  The number in the drive's drive
type register is unknown to the xp driver.
.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
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.
.PP
If the drive types and parameters are not initialized, the
.I xp
driver uses drive type registers to discern the type of disk attached
to each drive.  Because of numbering conflicts, foreign disks and/or
controllers frequently cause this automatic recognition scheme to fail.