.TH DVHP 4
.UC
.SH NAME
dvhp \- Diva Comp V/Ampex 9300 moving-head disk
.SH 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 standard device names begin with ``dvhp'' followed by
the drive number and then a letter a-h for partitions 0-7 respectively.
The character ? stands here for a drive number in the range 0-7.
.PP
The origin and size of the partitions (in 512-byte sectors) on each drive are
as follows:
.PP
.nf
.ta .5i +\w'000000    'u +\w'000000    'u +\w'000000    'u +\w'000000    'u
Partitions:
	disk	start	length	cyls	function on drive 0
	dvhp?a	0	9405	0-14	/
	dvhp?b	9405	9405	15-29	swap
	dvhp?c	18810	241395	30-414	/usr
	dvhp?d	260205	250800	415-814	remainder of pack
	dvhp?e	18810	169290	30-299	alternate configuration
	dvhp?f	188100	156750	300-549	alternate configuration
	dvhp?g	313500	165528	550-814	alternate configuration
	dvhp?h	0	511005	0-814	whole pack
.DT
.fi
.PP
Special files should only be created for the
partitions that are actually used,
as the overlap in these addresses could lead to confusion otherwise.
.PP
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 therefore raw I/O is considerably more efficient when
many words are transmitted.  The names of the raw files
conventionally begin with an extra `r.'
.PP
In raw I/O counts should be a multiple of 512 bytes (a disk sector).
Likewise
.I lseek
calls should specify a multiple of 512 bytes.
.SH FILES
.ta 2i
/dev/dvhp[0-7][a-h]	block files
.br
/dev/rdvhp[0-7][a-h]	raw files
.SH SEE ALSO
hk(4), hp(4), hs(4), ml(4), rf(4), rk(4), rl(4), rm(4), rp(4), rx2(4), xp(4)
.SH DIAGNOSTICS
\fBdvhp%d%c: hard error bn %d cs2=%b er1=%b\fP.  An unrecoverable
error occured during transfer of the specified sector of the specified
disk partition.  The contents of the two error registers are also printed
in octal and symbolically with bits decoded.
The error was either unrecoverable, or a large number of retry attempts
(including offset positioning and drive recalibration) could not
recover the error.
.PP
\fBdvhp%d: write locked\fP.  The write protect switch was set on the drive
when a write was attempted.  The write operation is not recoverable.
.PP
\fBdvhp%d%c: soft ecc bn %d\fP.  A recoverable ECC error occurred on the
specified sector of the specified disk partition.  This happens normally
a few times a week.  If it happens more frequently than
this the sectors where the errors are occuring should be checked to see
if certain cylinders on the pack, spots on the carriage of the drive
or heads are indicated.
.SH BUGS
In raw I/O
.I read
and
.IR write (2)
truncate file offsets to 512-byte block boundaries,
and
.I write
scribbles on the tail of incomplete blocks.
Thus,
in programs that are likely to access raw devices,
.I read, write
and
.IR lseek (2)
should always deal in 512-byte multiples.
.PP
DEC-standard error logging should be supported.
.PP
Bad block forwarding is not yet supported.
.PP
A program to analyze the logged error information (even in its
present reduced form) is needed.
.PP
The partition tables for the file systems should be read off of each
pack, as they are never quite what any single installation would prefer,
and this would make packs more portable.