Content-type: text/html Man page of ra

ra

Section: Environments, Tables, and Troff Macros (7)
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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 DIGITAL 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???  

RELATED INFORMATION

disklabel(8), MAKEDEV(8), uerf(8) delim off


 

Index

NAME
SYNOPSIS
DESCRIPTION
Disk Support
FILES
RELATED INFORMATION

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Time: 02:40:19 GMT, October 02, 2010