Thanks for a great tool. This has saved me a lot of time when doing initial mysqld setups.

However, I found an issue when running against mysql cluster (on the "server" node of course) where some variables don't quite work out:

Argument "NULL" isn't numeric in addition (+) at ./mysqltuner.pl line 256 (#1)
(W numeric) The indicated string was fed as an argument to an operator
that expected a numeric value instead. If you're fortunate the message
will identify which operator was so unfortunate.

Use of uninitialized value in concatenation (.) or string at ./mysqltuner.pl
line 609 (#2)
(W uninitialized) An undefined value was used as if it were already
defined. It was interpreted as a "" or a 0, but maybe it was a mistake.
To suppress this warning assign a defined value to your variables.

To help you figure out what was undefined, perl tells you what operation
you used the undefined value in. Note, however, that perl optimizes your
program and the operation displayed in the warning may not necessarily
appear literally in your program. For example, "that $foo" is
usually optimized into "that " . $foo, and the warning will refer to
the concatenation (.) operator, even though there is no . in your
program.

I will check this post periodically should you need more information.