rz.4

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)rz.4	2.1	3/10/87
.TH rz 4
.SH Name
rz \- SCSI disk interface
.SH Syntax
.ta .2i 1.5i 2.3i 3.4i
VAX NCR 5380:
.br
	\fBadapter	uba0	at nexus?    
.br
	controller	scsi0	at uba0	csr 0x200c0080  vector szintr 
.br
	disk	rz0	at scsi0	drive 0\fP
.PP
VAX DEC SII:
.br
	\fBadapter	ibus0	at nexus?    
.br
	controller	sii0	at ibus?	vector sii_intr 
.br
	disk	rz0	at sii0	drive 0\fP
.PP     
RISC DEC SII:
.br
	\fBadapter	ibus0	at nexus?    
.br
	controller	sii0	at ibus?	vector sii_intr 
.br
	disk	rz0	at sii0	drive 0\fP
.PP     
RISC DEC KZQ:
.br
	\fBadapter	uba0	at nexus?    
.br
	controller	kzq0	at ibus? csr 0761300	vector sii_intr 
.br
	disk	rz0	at kzq0	drive 0\fP
.PP
RISC NCR ASC:
.br
	\fBadapter	ibus0	at nexus?    
.br
	controller	asc0	at ibus?	vector ascintr 
.br
	disk	rz0	at asc0	drive 0\fP
.SH Description
.NXR "rz interface" "SCSI disk interface"
.NXR "SCSI disk interface"
.NXR "uda interface" "SCSI disk interface"
.PP
The 
.PN rz
driver is for all Digital SCSI disk drives.
.PP
The following rules are used to determine the major and minor numbers that 
are associated with an 
.PN rz
type disk.  There is one major number used to represent  
.PN rz 
disks.  The major number represents 32 disks.
The minor number is used to represent the both the SCSI unit
number and partition.  A disk partition refers to a designated portion
of the physical disk.
To accomplish this, the 8-bit minor number is broken up
into two parts.  The low three bits of the minor number specify a disk
partition.  These three bits allow for the naming of eight partitions.  The
partitions have a letter, a through h, as their name.  
The upper five bits of the minor
number specify the SCSI unit number within a group of 32 disks.
.PP
The device special file names associated with 
.PN rz 
disks are based on 
the following conventions.  These conventions are closely associated with
the minor number assigned to the disk. 
The standard device names begin with
.PN rz 
for the block special file and
.PN rrz 
for the raw (character) special file.
Following the
.PN rz
is the logical unit number and then a letter, a through h, to represent
the partition.  Throughout this reference page, the question mark (?) 
character represents
the logical unit number in the name of the device special file.  For example,
rz?b could represent rz0b, rz1b, and so on.
.PP
The following examples illustrate how the SCSI unit number is
calculated given the major and minor number of an 
.PN rz
disk.  For the device special file rrz6a, the major number is 56 and the
minor number is 48.  The partition is represented by the lower three
bits of the number 48.  The lower 
three bits are 0, which specifies the ``a'' partition.  The
upper five bits of 48 specify the number 6.  The major number is 56.  Because
56 is the base major number, it represents the group of 32 disks. 
Putting all these pieces together reveals that the major/minor pair 56/48
refers to the ``a'' partition of SCSI unit 6. 
.PP
The disk can be accessed through either the block special file or the 
character special file.  The block special file accesses the disk using
the file system's normal buffering mechanism.  Reads and writes to the block
special file can specify any size.  This avoids the need to limit data 
transfers to the size of physical disk records and to calculate offsets
within disk records.
The file system can break up large read and write requests into smaller 
fixed size transfers to the disk.
.PP
The character special file provides a raw interface that allows for
direct transmission between the disk and the user's read or write buffer.
In contrast to the block special file, reads and writes to the raw interface
must be done on full sectors only.  
For this reason, 
in raw I/O, counts must be a multiple of 512 bytes (a disk sector).
In the same manner,
.PN seek
calls must specify a multiple of 512 bytes.
A single read or write to the raw interface results in 
exactly one I/O operation.
Consequently raw I/O may be considerably more efficient for large transfers.
Multiply buffered I/O operations are
possible to any raw SCSI device. (See 
.MS nbuf 4 
for more information.)
.PP
For systems with SCSI disks, the first boot of the ULTRIX software after
the system is powered on may take longer than expected. This delay is
normal and is caused by the software spinning up the SCSI disk drives.
.SS Disk Support
.NXR "SCSI disk interface" "disk support"
This driver handles all disk drives that can be connected to the SCSI bus.
Consult the 
.I "ULTRIX Software Product Description" 
to determine which drives
are supported for which CPU types and hardware configurations.
.PP
The starting location and length (in 512 byte sectors) 
of the disk partitions of each
drive are shown in the following table.
Partition sizes can be changed by 
.MS chpt 8 .
For further information, see 
.MS dkio 4 .
.PP
.NXR "SCSI disk interface" "partition tables"
.nf
.ta .5i +\w'000000    'u +\w'000000    'u +\w'000000	'u +\w'000000	 'u
.PP
.B "RZ22 partitions"
	disk	start	length
.sp
	rz?a	0	32768
	rz?b	32768	69664
	rz?c	0	102431
	rz?d	0	0
	rz?e	0	0
	rz?f	0	0
	rz?g	0	0
	rz?h	0	0
.PP
.B "RZ23 partitions"
	disk	start	length
.sp
	rz?a	0	32768
	rz?b	32768	66690
	rz?c	0	204864
	rz?d	99458	35135	
	rz?e	134593	35135
	rz?f	169728	35136
	rz?g	99458	105406
	rz?h	134593	70271
.PP
.B "RZ23L partitions"
	disk	start	length
.sp
	rz?a	0	32768
	rz?b	32768	66690
	rz?c	0	237588
	rz?d	99458	35135	
	rz?e	134593	35135
	rz?f	169728	67860
	rz?g	99458	138130
	rz?h	134593	102995
.PP
.B "RZ24 partitions"
	disk	start	length
.sp
	rz?a	0	32768
	rz?b	32768	131072
	rz?c	0	409792
	rz?d	163840	81984
	rz?e	245824	81984
	rz?f	327808	81984
	rz?g	163840	245952
	rz?h	0	0
.PP
.B "RZ55 partitions"
	disk	start	length
.sp
	rz?a	0	32768
	rz?b	32768	131072
	rz?c	0	649040
	rz?d	163840	152446
	rz?e	316286	152446
	rz?f	468732	180308
	rz?g	163840	485200
	rz?h	0	0
.PP
.B "RZ56 partitions"
	disk	start	length
.sp
	rz?a	0	32768
	rz?b	32768	131072
	rz?c	0	1299174
	rz?d	163840	292530
	rz?e	456370	292530
	rz?f	748900	550273
	rz?g	163840	1135334
	rz?h	731506	567668
.PP
.B "RZ57 partitions"
	disk	start	length
.sp
	rz?a	0	32768
	rz?b	32768	184320
	rz?c	0	2025788
	rz?d	831488	299008
	rz?e	1130496	299008
	rz?f	1429504	596284
	rz?g	217088	614400
	rz?h	831488	1194300
.PP
.B "RRD40/RRD42 (read only) partitions"
	disk	start	length
.sp
	rz?a	0	(size varies per CD)
	rz?b	0	0
	rz?c	0	(size varies per CD)
	rz?d	0	0
	rz?e	0	0
	rz?f	0	0
	rz?g	0	0
	rz?h	0	0
.PP
.B "RX23 partitions"
	disk	start	length
.sp
	rz?a	0	2879
	rz?b	0	0
	rz?c	0	2879
	rz?d	0	0
	rz?e	0	0
	rz?f	0	0
	rz?g	0	0
	rz?h	0	0
.PP
.B "RX26 partitions"
	disk	start	length
.sp
	rz?a	0	5759
	rz?b	0	0
	rz?c	0	5759
	rz?d	0	0
	rz?e	0	0
	rz?f	0	0
	rz?g	0	0
	rz?h	0	0
.PP
.B "RX33 partitions"
	disk	start	length
.sp
	rz?a	0	2400
	rz?b	0	0
	rz?c	0	2400
	rz?d	0	0
	rz?e	0	0
	rz?f	0	0
	rz?g	0	0
	rz?h	0	0
.DT
.fi
.PP
Usually, the rz?a partition is used for the root file system and
the rz?b partition as a paging area.
The rz?c partition is used for disk-to-disk copying because 
it maps the entire disk.
.SH Files
.PN /dev/rz???
.br
.PN /dev/rrz???
.SH See Also
nbuf(4), dkio(4), SCSI(4), chpt(8), MAKEDEV(8), uerf(8)