Mark Post writes:
> >>> On 5/18/2016 at 04:27 PM, Malcolm Beattie <[email protected]> wrote:
> -snip-
> > So an ad hoc and quick and dirty way to write a couple of tracks
> > of a lone R0 that'll be treated by Linux as "n/f" is (starting
> > with DASD device 777 offline):
>
> Cool, it does indeed work. So I wrapped a script around that and uploaded it
> to http://wiki.linuxvm.org/wiki/Projects_and_Software/Scripts for anyone
> that's interested in it.
>
> Bug reports are welcome, but don't expect rapid turnaround. :)
Having the following "llunformat" as the low-level script that does
the unformatting (invoke as "llunformat devno") may be preferable in
terms of keeping people's lunch down compared to the Perl one-liner:
#!/usr/bin/perl
# Copyright 2016 IBM United Kingdom Ltd
# Author: Malcolm Beattie, IBM
# Last update: 19 May 2016
# Sample code - NO WARRANTY
#
use strict;
sub ckd {
my ($c, $h, $r, $key, $data) = @_;
my $count = pack("nnCCn", $c, $h, $r, length($key), length($data));
return $count . $key . $data;
}
sub track {
my ($data) = @_;
return $data . ("\xff" x 8) . ("\0" x (65536 - 8 - length($data)));
}
my $devno = shift @ARGV or die "Usage: llunformat devno\n";
my $dev = sprintf("/dev/disk/by-path/ccw-0.0.%04s", $devno);
my @cmd = (qw(dd bs=65536 oflag=direct), "of=$dev");
open(DD, "|-", @cmd) or die "dd: $!\n";
for (my $h = 0; $h < 2; $h++) {
print DD track(ckd(0, $h, 0, "", "\0" x 8));
}
--Malcolm
--
Malcolm Beattie
Linux and System z Technical Consultant, zChampion
IBM UK Systems and Technology Group
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