4BSD/usr/man/cat4/rk.4

RK(4)               UNIX Programmer's Manual                RK(4)



NAME
     rk - RK-11/RK07

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 RK-07 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 pro-
     vides a 10Mbyte paging area.  Otherwise partition 2 on the
     other drive is used as a single large file system.

     The _r_k 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
     operation and therefore raw I/O is considerably more effi-
     cient when many words are transmitted.  The names of the raw
     RK files begin with _r_r_k and end with a number which selects
     the same disk as the corresponding _r_k 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 _s_e_e_k calls should specify a multiple of 512 bytes.

FILES
     /dev/rk?, /dev/rrk?

BUGS
     In raw I/O _r_e_a_d and _w_r_i_t_e(2) truncate file offsets to 512-
     byte block boundaries, and _w_r_i_t_e scribbles on the tail of
     incomplete blocks.  Thus, in programs that are likely to
     access raw devices, _r_e_a_d, _w_r_i_t_e and _l_s_e_e_k(2) should always
     deal in 512-byte multiples.



Printed 11/10/80                                                1