After some days looking for how to solve this annoying exception:

ERROR 2999: Unexpected internal error. Failed to create DataStorage

I think that this is best solution (after all is on Apache-FAQ): Apache - FAQ - Q: What shall I do if I saw "Failed to create DataStorage"?

On few words:

1. deploy with ant: "ant"
2. copy your hadoop jars (core and test) to /path/to/pig/build/ivy/lib/Pig
3. I did something else: modify at libraries.properties the version of hadoop (core and test). This file is at /path/to/pig/ivy/libraries.properties.
4. deploy with ant: "ant" again
5. copy your pig.jar and rename as pig-<version>-core.jar

and it should work!

P.S.: This issue will be solved in Pig 0.9.1 and beyond.