I'm not altogether sure what you are after, but maybe the following does it?

use strict;
use warnings;

my %vhosts;
my $host;

#open (LSMAP, "-|", "/usr/ios/cli/ioscli lsmap -all") or die $!;
while (defined(my $lsm = <DATA>)) {
    if ($lsm =~ /^Backing device\s+(\w+)\.\w+$/) {
        push @{$vhosts{$host}}, $1;
        next;
    }
    
    my ($p1, $p2, $p3) = split /\s+/, $lsm;

    $host = $p1 if defined $p3 && $p1 !~ /^(SVSA|-+)$/;
}

for my $host (sort keys %vhosts) {
    print "lu -map -clustername asccl-eta1 -sp stp-eta1 -vadapter $hos
+t -lu $_\n"
        for @{$vhosts{$host}};
}

__DATA__
SVSA            Physloc                                      Client Pa
+rtition ID
--------------- -------------------------------------------- ---------
+---------
vhost0          U9117.MMD.218A8B7-V1-C2                      0x0000000
+b

VTD                   vtscsi0
Status                Available
LUN                   0x8100000000000000
Backing device        l02duapofdev_r1.58ff94782d7c325acc49a8dd9c04bb1e
Physloc
Mirrored              N/A

VTD                   vtscsi1
Status                Available
LUN                   0x8200000000000000
Backing device        l02duapofdev_b1.0ee86903d4951ce38a9b691b322ff1d2
Physloc
Mirrored              N/A

SVSA            Physloc                                      Client Pa
+rtition ID
--------------- -------------------------------------------- ---------
+---------
-------------------------------------------- ------------------
vhost3          U9117.MMD.218A8B7-V1-C14                     0x0000000
+0

VTD                   NO VIRTUAL TARGET DEVICE FOUND

SVSA            Physloc                                      Client Pa
+rtition ID
--------------- -------------------------------------------- ---------
+---------
vhost5          U9117.MMD.218A8B7-V1-C16                     0x0000000
+7

VTD                   vtscsi22
Status                Available
LUN                   0x8100000000000000
Backing device        l02duapofqa_r1.4746343ea4f12fe1092615c8734d9844
Physloc
Mirrored              N/A

VTD                   vtscsi23
Status                Available
LUN                   0x8200000000000000
Backing device        l02duapofqa1_d1.449583501d812f69e6189ea7f4a29e06
Physloc
Mirrored              N/A
[download]

Prints:

lu -map -clustername asccl-eta1 -sp stp-eta1 -vadapter vhost0 -lu l02d
+uapofdev_r1
lu -map -clustername asccl-eta1 -sp stp-eta1 -vadapter vhost0 -lu l02d
+uapofdev_b1
lu -map -clustername asccl-eta1 -sp stp-eta1 -vadapter vhost5 -lu l02d
+uapofqa_r1
lu -map -clustername asccl-eta1 -sp stp-eta1 -vadapter vhost5 -lu l02d
+uapofqa1_d1
[download]

It's more about "what you want" rather than "what you don't want".