term% cat index.txt RK(4) Kernel Interfaces Manual 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 phys‐
ical disk records. There is also a `raw' interface which provides for
direct transmission between the disk and the user's read or write buf‐
fer. 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 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 incomplete blocks.
Thus, in programs that are likely to access raw devices, read, write
and lseek(2) should always deal in 512-byte multiples.
RK(4)