Dadisi is an API to create and test data distribution policies in a (simulated) storage environment. With it you can create a virtual storage architecture and fill it with "data" that will be placed according to your description.
Racer is a driving simulator for several OS's. This is an easy to use GUI driven program that renames the folders and files and alters the .ini and .shd files so the Linux experience can now be just as great as the other OS experience.
IITK OSD Simulator Project at Indian Institute of Technolgy,Kanpur is an implementation of simulator for object based storage device(OSD). This package contains OSD-iSCSI module and T10 compliant OSD simulator. Support for Collections is provided.