#! perl -slw
use strict;
use Data::Dump qw[ pp ];

my %hash;

while( <DATA> ) {
    chomp;
    my $r = \%hash;
    my @bits = split '\s+->\s+|_', $_;
    $r = $r->{ shift( @bits ) } //= {} while @bits > 2;
    $r->{ $bits[ 0 ] } = $bits[ 1 ];
}

pp \%hash;

__DATA__
Host_001 -> objectID -> HOST.62
Host_001 -> name -> rapidqa
Host_001_WWN_001 -> WWN -> 21.00.00.E0.8B.80.7E.7D
Host_001_WWN_002 -> WWN -> 21.00.00.E0.8B.80.E7.7F
Host_001_LogicalUnit_001 -> objectID -> LU.R700.87108.8234
Host_001_LogicalUnit_001 -> devNum -> 8234
Host_001_LogicalUnit_002 -> objectID -> LU.R700.87108.8235
Host_001_LogicalUnit_002 -> devNum -> 8235
Host_002 -> objectID -> HOST.107
Host_002 -> name -> sapfvir03
Host_002_WWN_001 -> WWN -> 21.00.00.E0.8B.81.D7.F6
Host_002_WWN_002 -> WWN -> 21.00.00.E0.8B.81.4C.F9
Host_002_LogicalUnit_001 -> objectID -> LU.R700.87108.10336
Host_002_LogicalUnit_001 -> devNum -> 10336