Something similar to trizen's solution #4.

1. make an hash (%seen, %present, %toskip...) from your first array
2. grep {} the second array

#!/usr/bin/perl -w
use strict;

my @blacklist = qw ( server1 server2 server3 server5 );
my %blacklisted = map { $_ => 1 } @blacklist;
my @candidate = <DATA>;
chomp @candidate;
my @servers = grep { not $blacklisted{$_} } @candidate;
print "@servers";

__DATA__
server2
server5
server7
server8
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