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.Dd December 20, 2006
.Dt TCOPY 1
.Os
.Sh NAME
.Nm tcopy
.Nd copy and/or verify mag tapes
.Sh SYNOPSIS
.Nm
.Op Fl cvx
.Op Fl s Ar maxblk
.Oo Ar src Op Ar dest
.Oc
.Sh DESCRIPTION
The
.Nm
utility is designed to copy magnetic tapes.
The only assumption made
about the tape layout is that there are two sequential EOF marks
at the end.
By default, the
.Nm
utility will print
information about the sizes of records and files found
on the
.Pa /dev/sa0
tape, or on the tape specified by the
.Ar src
argument.
If a destination tape is also specified by the
.Ar dest
argument, a copy of the source tape will be made.
The blocking on the
destination tape will be identical to that used on the source tape.
Copying
a tape will yield the same program output as if just printing the sizes.
.Pp
The following options are available:
.Bl -tag -width ".Fl s Ar maxblk"
.It Fl c
Copy
.Ar src
to
.Ar dest
and then verify that the two tapes are identical.
.It Fl s Ar maxblk
Specify a maximum block size,
.Ar maxblk .
.It Fl v
Given the two tapes
.Ar src
and
.Ar dest ,
verify that they are identical.
.It Fl x
Output all informational messages to the standard error
instead of the standard output.
This option is useful when
.Ar dest
is given as
.Pa /dev/stdout .
.El
.Sh SEE ALSO
.Xr mt 1 ,
.Xr mtio 4
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .
.Sh BUGS
.Bl -item
.It
Modern tape drives may return a SCSI "Incorrect Length Indicator (ILI)"
for each read with a different block size that what is on the
tape, and that slows things down a lot.
This can be disabled with the
.Xr mt 1
command:
.Bd -literal -offset indent
$ mt param sili -s 1
.Ed
.It
Writing an image of a tape to a file does not preserve much more than
the raw data.
Block size(s) and tape EOF marks are lost which would
otherwise be preserved in a tape-to-tape copy.
.It
End of data (EOD) is determined by two sequential EOF marks
with no data between them.
There used to be old systems which typically wrote three EOF's between tape
files.
The
.Nm
utility will erroneously stop copying early in this case.
.It
When using the copy/verify option
.Fl c ,
.Nm
does not rewind the tapes prior to start.
A rewind is performed
after writing, prior to the verification stage.
If one does not start
at the beginning-of-tape (BOT) then the comparison
may not be of the intended data.
.El