A method for balancing load among virtual storage drives is disclosed. In one embodiment, such a method includes providing multiple storage drives and dividing each storage drive into multiple virtual storage drives. The method further creates RAID arrays from the virtual storage drives. Each RAID array is made up of extents that are striped across its virtual storage drives. The method tracks I/O to each virtual storage drive to determine which virtual storage drives have high I/O traffic and which virtual storage drives have low I/O traffic. The virtual storage drives are correlated to their respective RAID arrays. The method migrates extents from RAID arrays having virtual storage drives with high I/O traffic to RAID arrays having virtual storage drives with low I/O traffic. A corresponding system and computer program product are also disclosed.