When you read @DATA from your DB, you could split it up into a hash of arrays keyed on hostid...in fact, you could split all your data at this point, to avoid the split in your main loop...

foreach (@DATA) {
   ($hostid, $time, $get, $post, $conn) = split(/\t/);
   push @{$munged_data{$hostid}},
      {time => $time,get => $get,post=>$post,conn=>$conn};
}
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...allowing you to then do something like...

foreach my $server (@servers) {
   foreach(@{$munged_data{$server}}) {
     #do stuff with $_->{time} etc.
   }
}
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Alternatively, you could look into splitting the data when it gets written into the db in the first place if this is possible, which would presumably involve configuring whatever logging module it is you're using.

Cheers, Ben.