4BSD/usr/man/cat4/up.4

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



NAME
     up - emulex sc21/ampex 9300 UNIBUS 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:

     9300 partitions
          disk      start     byte
          0         0         15884
          1         16416     33440
          2         0         500992
          3         341696    15884
          4         358112    55936
          5         414048    36944
          6         341696    159296
          7         49856     291346

     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/up[0-3][a-h]   block files
     /dev/rup[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                                                1