4BSD/usr/man/cat4/hp.4

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



NAME
     hp - RP06, RM03, RM-05 moving-head disk

DESCRIPTION
     Files with minor device numbers 0 through 7 refer to various
     portions of drive 0; minor devices 8 through 15 refer to
     drive 1, etc.

     The origin and size of the pseudo-disks on each drive are as
     follows:

     RP03 partitions
          disk      start     length
          0         0         15884
          1         15884     33440
          2         40964     8360
          3         0         0
          4         0         0
          5         0         0
          6         49324     291346
          7         0         0

     RM03 partitions
          disk      start     length
          0         0         15884
          1         16000     33440
          2         0         0
          3         0         0
          4         0         0
          5         0         0
          6         49600     82080
          7         0         0

     RM05 partitions
          disk      start     length
          0         0         15884
          1         16416     33440
          2         0         500992
          3         341696    15884
          4         358112    55936
          5         414048    36944
          6         341696    159296
          7         49856     291346

     It is unwise for all of these files to be present in one
     installation, since there is overlap in addresses and pro-
     tection becomes a sticky matter.  Ordinarily devices 0 and 6
     on rp06 and rm03 drives, and 0, 7, and either 6 or 5, 6, and
     7 on rm05 drives.  Note that the file system sizes are
     chosen to allow the partitions to be copied between the
     rp06's and rm05's.  This is done so that systems with mixed
     drives will be able to rearrange file systems easily (see



Printed 11/10/80                                                1






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



     also _u_p(4)).  Device 2 is the entire pack, and is used in
     pack-to-pack copying.

     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.  There is also a `raw'
     interface which 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 there-
     fore raw I/O is considerably more efficient when many words
     are transmitted.  The names of the raw files conventionally
     begin with an extra `r.'

FILES
     /dev/rp[0-3][a-h]   block files
     /dev/rrp[0-3][a-h]  raw files

SEE ALSO
     rp(4)

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                                                2