use strict;
use warnings;

local $/="\narray ";
while (<DATA>){
	s/\n(?!unassigned)(:?array)?/ /g;
	print  my $row=(m/^array/?"":"array "). "$_\n";
}
__DATA__
array A
physicaldrive 2C:1:1 port 2C:box 1:bay 1 SAS 1 TB OK
physicaldrive 2C:1:2 port 2C:box 1:bay 2 SAS 1 TB OK
array B
... etc ...
unassigned
physicaldrive 7C:3:7 port 7C:box 3:bay 7 SAS 1 TB OK
...