With this, I throw my code into the ring:

Update: My apologies -- I missed the part about the huge datafile. This method stores everything in memory, so that could be a problem...

#!/perl/bin/perl -w

use strict;
use Data::Dumper;

my $spec     = 'A9A10A10A15';
my $hash     = {};
my $nodename = "";
my $out      = {};

$_ = <DATA>; # skip the header line

while (<DATA>) { #stuff everything into a hash of array refs
  my @arr  = unpack($spec, $_);
  @arr = map { s/^\s+//; $_ } @arr; # remove any leading spaces
  if ($arr[0]) {
    $nodename = shift(@arr);
  }
  else {
    shift(@arr);
  }
  push(@{$hash->{$nodename}}, \@arr);
}

print Dumper($hash); # contents may be viewed in $VAR1 below

for my $key (keys %$hash) {
  my $rows = $hash->{$key};
  for (my $rownum = 0; $rownum <= $#$rows; $rownum++) {
    my $cols = $rows->[$rownum];
    for (my $col = 0; $col <= $#$cols; $col++) {

      # include a space between the date/time strings
      my $space = ($rownum == 0 && $col == 2) ? ' ' : '';
      $out->{$key}->[$col] .= $cols->[$col] . $space;
    }  
  }
}

for my $key (keys %$out) {
  printf "%-7s %-25s %-29s %-30s\n", $key, @{$out->{$key}};
}

__DATA__
NodeName FileName  PathName  BackupDate
BD3101   bananaswi \breakfa       2007-03-06
         ithapple  st\fruit  14:02:31.000000
         s.gif     s\tree\
TP4223   chocolate \sweet\d       2006-02-28
         caramelfu esserts\  21:16:41.000000
         dge.gif   hersheys\
EO2123   tofuwith  \organic\      2007-07-16
         peas.gif  vegetable 13:55:06.000000
                   s\legumes\

__OUTPUT__
$VAR1 = {
          'TP4223' => [
                        [
                          'chocolate',
                          '\\sweet\\d',
                          '2006-02-28'
                        ],
                        [
                          'caramelfu',
                          'esserts\\',
                          '21:16:41.000000'
                        ],
                        [
                          'dge.gif',
                          'hersheys\\',
                          ''
                        ]
                      ],
          'BD3101' => [
                        [
                          'bananaswi',
                          '\\breakfa',
                          '2007-03-06'
                        ],

           ... etc ...

TP4223  chocolatecaramelfudge.gif \sweet\desserts\hersheys\     2006-0
+2-28 21:16:41.000000
BD3101  bananaswiithapples.gif    \breakfast\fruits\tree\       2007-0
+3-06 14:02:31.000000
EO2123  tofuwithpeas.gif          \organic\vegetables\legumes\  2007-0
+7-16 13:55:06.000000
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