#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my (%data, $device);
while (my $line = <DATA>){
  chomp $line;
  next if $line =~ /^\s*$/;
  if ($line =~ /logging to ([\w-]+)/){
    $device = $1;
    next;
  }
  push @{$data{$device}}, $line;
}

print Dumper(\%data);
  
__DATA__
 logging to device1 is 2.3.5.1 . . .
 
56% /var
38% /
31% Interleaved
device1
Tue Sep  9 11:26:44 ist 2005
 	
 logging to device2 is 2.3.5.1 . . .
 

96% /var
88% /
100% Interleaved
device2
Tue Sep  5 10:26:44 GMT 2005

logging to device5-PPP is 2.3.5.1 . . .
 
156% /var
138% /
131% Interleaved
device1
Tue Sep  9 11:26:44 ist 2005
 	
 logging to device8-PPm is 2.3.5.1 . . .
 
596% /var
688% /
100% Interleaved
device2
Tue Sep  5 10:26:44 GMT 2005