man(1) Manual page archive


     HP(4)                                                       HP(4)

     NAME
          hp - RH-11/RP04, RP05, RP06 moving-head disk

     DESCRIPTION
          The octal representation of the minor device number is
          encoded idp, where i is an interleave flag, d is a physical
          drive number, and p is a pseudodrive (subsection) within a
          physical unit.  If i is 0, the origins and sizes of the
          pseudodisks on each drive, counted in cylinders of 418 512-
          byte blocks, are:

               disk start     length
               0    0    23
               1    23   21
               2    0    0
               3    0    0
               4    44   386
               5    430  385
               6    44   367
               7    44   771

          If i is 1, the minor device consists of the specified pseu-
          dodisk on drives numbered 0 through the designated drive
          number.  Successively numbered blocks are distributed across
          the drives in rotation.

          Systems distributed for these devices use disk 0 for the
          root, disk 1 for swapping, and disk 4 (RP04/5) or disk 7
          (RP06) for a mounted user file system.

          The block files access the disk via the system's normal
          buffering mechanism and may be read and written without
          regard to physical disk records.

          A `raw' interface provides for direct transmission 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 efficient when many
          words are transmitted.  The names of the raw files conven-
          tionally begin with an extra `r.'  In raw I/O the buffer
          must begin on a word boundary, and raw I/O to an interleaved
          device is likely to have disappointing results.

     FILES
          /dev/rp?, /dev/rrp?

     SEE ALSO
          rp(4)

     BUGS

     HP(4)                                                       HP(4)

          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.

          Raw device drivers don't work on interleaved devices.