Comparing DLm to mainframe VTLs
EMC's DLM should be more properly compared to mainframe VTLs than open systems VTLs. IBM's TS7700 supports 12 FICON links, like EMC's DLm, and supports IBM's 3592 format (superseded 3590) and TS1100 drives. Three of them can be grid'd together. A TS7700 offers a maximum of 768 virtual drives and 1,000,000 virtual volumes. Sun's VSM5 offers a capacity of up to 90TB, uses 15K disk drives, supprts StorageTEk tape formats, and supports up to 16 FICON channels. Multiple VSMs can be interconnected. EMC's DLm uses 1TB SATA drives in contrast to Sun's 15K FC drives. EMC's DLm supports 3480, 3490 and 3590 tape formats but not IBM's newer 3592. The DLM can have up to six virtual tape engines (VTEs) but EMC doesn't say how many virtual tyape drives that means. Have a look at CentricStor, Bus-Tech and Shoden mainframe VTLs as well.