man(1) Manual page archive


     RK(4)                                                       RK(4)

     NAME
          rk  -  RK-11/RK03 or RK05 disk

     DESCRIPTION
          Rk? refers to an entire disk as a single sequentially-
          addressed file.  Its 256-word blocks are numbered 0 to 4871.
          Minor device numbers are drive numbers on one controller.

          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 seek 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.