EMC Disk Library for mainframe (DLm) enables IBM zSeries mainframe customers to augment or eliminate mainframe traditional tape libraries and virtual tape libraries from their data centers. Disk Library for mainframe can give you up to 1.2 PB of usable capacity (3 PB of tape information with typical compression) and up to 1.2 GB/s of throughput, and can emulate up to 1,536 tape drives in one system.