[unix-history] / usr / man / man4 / hp.4

.TH HP 4 
.SH NAME
hp \- RH-11/RP04, RP05, RP06 moving-head disk
.SH DESCRIPTION
The octal representation of the minor device number is encoded
.IR idp ,
where
.I i
is an interleave flag,
.I d
is a physical drive number,
and
.I p
is a pseudodrive (subsection) within a physical unit.
If
.I i
is 0,
the origins and sizes of the pseudodisks on each drive,
counted in cylinders of 418 512-byte blocks, are:
.nf
.PP
	disk	start	length
	0	0	23
	1	23	21
	2	0	0
	3	0	0
	4	44	386
	5	430	385
	6	44	367
	7	44	771
.fi
.PP
If
.I i
is 1, the minor device consists of the specified 
pseudodisk on drives numbered 0 through the designated
drive number.
Successively numbered blocks are distributed
across the drives in rotation.
.PP
Systems distributed for these devices
use disk 0 for the root, disk 1 for swapping, and
disk 4 (RP04/5) or disk 7 (RP06) for a mounted
user file system.
.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.
.PP
A `raw' interface
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 boundary,
and raw I/O to an interleaved device is likely to have
disappointing results.
.SH FILES
/dev/rp?, /dev/rrp?
.SH SEE ALSO
rp(4)
.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
Raw device drivers don't work on interleaved devices.
Commit	Line	Data
70b96c2d DR	1	.TH HP 4
	2	.SH NAME
	3	hp \- RH-11/RP04, RP05, RP06 moving-head disk
	4	.SH DESCRIPTION
	5	The octal representation of the minor device number is encoded
	6	.IR idp ,
	7	where
	8	.I i
	9	is an interleave flag,
	10	.I d
	11	is a physical drive number,
	12	and
	13	.I p
	14	is a pseudodrive (subsection) within a physical unit.
	15	If
	16	.I i
	17	is 0,
	18	the origins and sizes of the pseudodisks on each drive,
	19	counted in cylinders of 418 512-byte blocks, are:
	20	.nf
	21	.PP
	22	disk start length
	23	0 0 23
	24	1 23 21
	25	2 0 0
	26	3 0 0
	27	4 44 386
	28	5 430 385
	29	6 44 367
	30	7 44 771
	31	.fi
	32	.PP
	33	If
	34	.I i
	35	is 1, the minor device consists of the specified
	36	pseudodisk on drives numbered 0 through the designated
	37	drive number.
	38	Successively numbered blocks are distributed
	39	across the drives in rotation.
	40	.PP
	41	Systems distributed for these devices
	42	use disk 0 for the root, disk 1 for swapping, and
	43	disk 4 (RP04/5) or disk 7 (RP06) for a mounted
	44	user file system.
	45	.PP
	46	The
	47	block
	48	files
	49	access the disk via the system's normal
	50	buffering mechanism
	51	and may be read and written without regard to
	52	physical disk records.
	53	.PP
	54	A `raw' interface
	55	provides for direct transmission between the disk
	56	and the user's read or write buffer.
	57	A single read or write call results in exactly one I/O operation
	58	and therefore raw I/O is considerably more efficient when
	59	many words are transmitted.
	60	The names of the raw files
	61	conventionally
	62	begin with
	63	an extra `r.'
	64	In raw I/O the buffer must begin on a word boundary,
65	and raw I/O to an interleaved device is likely to have
66	disappointing results.
67	.SH FILES
68	/dev/rp?, /dev/rrp?
69	.SH SEE ALSO
70	rp(4)
71	.SH BUGS
72	In raw I/O
73	.I read
74	and
75	.IR write (2)
76	truncate file offsets to 512-byte block boundaries,
77	and
78	.I write
79	scribbles on the tail of incomplete blocks.
80	Thus,
81	in programs that are likely to access raw devices,
82	.I read, write
83	and
84	.IR lseek (2)
85	should always deal in 512-byte multiples.
86	.PP
87	Raw device drivers don't work on interleaved devices.