or, as your 'key' seems just to be an index, why not just use an array?

my @grp_advise = (
                       "normal,random,sequential",
                       "willneed,dontneed,free",
                       "access_lwp,access_many,access_default"
              );

for (my $grp_index = 0; $grp_index <= $#grp_advise; $grp_index++) {
        print "$grp_index  ===> $grp_advise[$grp_index]\n";

}
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