RK(4) RK(4)
NAME
rk - RK11/RK07 disk driver
DESCRIPTION
Files with minor device numbers 0 through 7 refer to various
portions of drive 0, minor devices 8 through 16 refer to
drive 1, etc.
The range and size of the pseudo-drives for each drive are
as follows:
RK07 partitions:
disk start length
0 0 15884
1 15906 10032
2 0 53780
3 0 0
4 0 0
5 0 0
6 26004 27786
7 0 0
On a dual RK07 system partition 0 is used for the root for
one drive and partition 6 for the /usr file system. If
large jobs are to be run, partition 1 on both drives
provides a 10Mbyte paging area. Otherwise partition 2 on
the other drive is used as a single large file system.
The rk files discussed above 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 transmis-
sion between the disk and the user's read or write buffer.
A single read or write call results in exactly one I/O oper-
ation and therefore raw I/O is considerably more efficient
when many words are transmitted. The names of the raw RK
files begin with rrk and end with a number which selects the
same disk as the corresponding rk file.
In raw I/O the buffer must begin on a word boundary, and
counts should be a multiple of 512 bytes (a disk block).
Likewise lseek(2) calls should specify a multiple of 512
bytes.
FILES
/dev/rk?, /dev/rrk?
BUGS
In raw I/O read and write(2) truncate file offsets to 512-
byte block boundaries, and write scribbles on the tail of
RK(4) RK(4)
incomplete blocks. Thus, in programs that are likely to
access raw devices, read, write and lseek(2) should always
deal in 512-byte multiples.