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ra(7)
NAME
ra - MSCP disk interface
SYNOPSIS
For XMI/KDM (only for the DEC 7000):
bus xmi0 at iop0 vector xmierror
controller uq0 at xmi? port kdm vector uqintr
device disk ra4 at uq0 drive 4
For XMI/CI/HSC (only for the DEC 7000):
bus xmi0 at iop0 vector xmierror
bus ci0 at xmi? port np vector cimna_isr
controller hsc6 at ci0 cinode 6
device disk ra1 at hsc6 drive 1
For ra devices dual ported between two controllers:
device disk ra3 at * drive 3
DESCRIPTION
This is a driver for all MSCP disk controllers. All controllers
communicate with the host through a packet-oriented protocol termed the
Mass Storage Control Protocol (MSCP).
The following rules are used to determine the major and minor numbers that
are associated with an ra disk type:
· There are two major numbers for an ra type disk, major number 23 and
major number 28.
· Major number 23 specifies an ra block device, and major number 28
specifies the ra character device file.
· Each major number represents up to 255 disks.
· The minor number is used to represent both the logical unit number and
the disk partition.
· A disk partition refers to a designated portion of the physical disk.
· To refer to both the logical unit number and the disk partition, the
20-bit minor number is broken up into two parts. The low three bits
(bits 0-2) allow for the naming of eight partitions. The partitions
are named a, b, c, d, e, f, g, and h. The upper fourteen bits of the
minor number specify the logical unit number. The maximum logical
unit number supported is 255, with the rest of the logical unit number
field reserved for future use.
The device special file names associated with ra disks are based on the
following conventions, which are closely associated with the minor number
assigned to the disk:
· The standard device names begin with ra for the block special file,
and rra for the raw (character) special file.
· Following the ra is the logical unit number and then a letter, a
through h, which specifies the partition. In this reference page, the
question mark (?) character represents the logical unit number in the
name of the device special file. For example ra?b could represent
devices ra0b, ra1b, and so on.
The following examples show how the logical unit number is calculated from
the major and minor number of an ra disk.
For the device special file rra6a, the major number is 28 and the minor
number is 384. The partition is represented by the lower 3 bits of the
number 384. The lower 3 bits will be 0 (zero), which specifies the a
partition. The upper 14 bits of 384 specifies the number 6. The major
number is 28. Putting all these pieces together reveals that the
major/minor pair 28/384 refers to the a partition of logical unit 6.
Similarly, the following example determines the logical unit number
corresponding to the major/minor pair 28/386. The low 3 bits of the minor
number specifies the number 2, which is the c partition. The upper 14 bits
of the minor number specifies the number 6. The major number is 28.
Therefore, the major/minor pair 28/386 refers to the c partition of logical
unit number 6 or rra6c.
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 may break up large read and write
requests into smaller fixed size transfers to the disk.
The character special file provides a raw interface that enables 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. Because of this, in raw I/O, counts
should be multiples of 512 bytes (a disk sector). In addition, seek calls
should 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.
Disk Support
This driver handles all disk drives that can be connected to an MSCP-based
controller. Consult the Software Product Description to determine which
controllers are supported for specific CPU types and hardware
configurations.
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 the disklabel command.
RA60 partitions
______________________
disk start length
______________________
ra?a 0 40960
ra?b 40960 41968
ra?c 0 400176
ra?d 242928 52416
ra?e 295344 52416
ra?f 347760 52416
ra?g 82928 160000
ra?h 242928 157248
______________________
RA70 partitions
______________________
disk start length
______________________
ra?a 0 40960
ra?b 40960 122880
ra?c 0 547041
ra?d 0 163840
ra?e 0 471040
ra?f 471040 76001
ra?g 163840 383201
______________________
RA71 partitions
________________________
disk start length
________________________
ra?a 0 131072
ra?b 131072 262144
ra?c 0 1367310
ra?d 393216 324698
ra?e 717914 324698
ra?f 1042612 324698
ra?g 393216 819200
ra?h 1212416 154894
________________________
RA72 partitions
________________________
disk start length
________________________
ra?a 0 131072
ra?b 131072 262144
ra?c 0 1953300
ra?d 393216 520028
ra?e 913244 520028
ra?f 1433272 520028
ra?g 393216 819200
ra?h 1212416 740884
________________________
RA73 partitions
________________________
disk start length
________________________
ra?a 0 131072
ra?b 131072 262144
ra?c 0 3920490
ra?d 393216 1175552
ra?e 1568768 1175552
ra?f 2744320 1176170
ra?g 393216 819200
ra?h 1212416 2708074
________________________
RA80 partitions
______________________
disk start length
______________________
ra?a 0 40960
ra?b 40960 41968
ra?c 0 237212
ra?d 82928 51428
ra?e 134356 51428
ra?f 185784 51428
ra?g 82928 154284
ra?h 0 0
______________________
RA81 partitions
______________________
disk start length
______________________
ra?a 0 81920
ra?b 81920 262144
ra?c 0 891072
ra?d 344064 182336
ra?e 526400 182336
ra?f 708736 182336
ra?g 344064 547008
ra?h 0 0
______________________
RA82 partitions
_______________________
disk start length
_______________________
ra?a 0 131072
ra?b 131072 262144
ra?c 0 1216665
ra?d 393216 274483
ra?e 667699 274483
ra?f 942182 274483
ra?g 393216 823449
ra?h 0 0
_______________________
RA90 partitions
________________________
disk start length
________________________
ra?a 0 131072
ra?b 131072 262144
ra?c 0 2376153
ra?d 393216 660979
ra?e 1054195 660979
ra?f 1715174 660979
ra?g 393216 819200
ra?h 1212416 1163737
________________________
RA92 partitions
___________________________
disk start length
___________________________
ra?a 0 131072
ra?b 131072 262144
ra?c 0 2940951
ra?d 393216 660979
ra?e 1054195 660979
ra?f 1715174 1225777
ra?g 393216 819200
ra?h 1212416 1728535
___________________________
ESE20 partitions
______________________
disk start length
______________________
ra?a 0 40960
ra?b 40960 42160
ra?c 0 245757
ra?d 82928 81416
ra?e 164344 81413
ra?f 0 0
ra?g 82928 162829
ra?h 0 0
______________________
Usually the ra?a partition is used for the root file system, and the ra?b
partition is used as a paging area. The ra?c partition is used for pack to
pack copying because it maps the entire disk.
FILES
/dev/ra???
/dev/rra???
SEE ALSO
dkio(4), disklabel(8), MAKEDEV(8), uerf(8)
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Index for
Section 7 |
|
|
Alphabetical
listing for R |
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Top of
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