EMC’s new VLT scales to half a petabyte

EMC also announced what Emsley called the first tapeless virtual tape library for use in IBM zSeries mainframe environments.

“A lot of people forget the mainframe is still alive and well,” Emsley said, and that most mission-critical applications are still run in a mainframe environment.

The Disk Library for Mainframe, or DLm, is entirely disk-based, unlike existing disk-tape hybrid virtual tape libraries. It connects to the zSeries through FICON or ESCON channels, unlike newer generations of tape.

“Not all VTLs can interoperate with mainframe systems, said Whitehouse. “Mainframes communicate though ESCON or FICON (Fibre Channel for mainframes) channels, which are not supported by more current tape technology. And even if they did, mainframes still can’t take advantage of the full capacity of LTO-3 or LTO-4 media.”

Tape use is more challenging in the mainframe world as opposed to open systems, Emsley said. Tape is used as a medium for production data and batch reporting, so its reliability doesn’t just affect backup, but also the production environment.

“Tape in mainframe environments is active storage in many cases,” Whitehouse said. “Tape media for mainframes is typically not used to its fullest capacity — there’s no concept of tape-spanning in the mainframe world — so the inefficiencies around tape are magnified. Issues have to do with tape handling, tape media size — small capacity means more tapes to handle — frequency of access to tape and the responsiveness (and) speed of tape. Seeking (and) positioning to needed information takes time.”

And there’s a reliability issue with the magnetic medium. “They fail,” Emsley said. “Bad media is bad news.” They can get lost and incur transport costs to restore. Tape is also becoming a scarcer commodity on the market, he said.

The DLm uses 1TB SATA II drives with RAID 6 protection. Emsley said the library can scale to 190TB of usable capacity. With mainframe hardware compression for backup at a ratio of about 2.5 to one, that’s half a petabyte of storage, Emsley said. And the DLM delivers throughput of up to 600 Mbps.

Once full, a loaded DLm can be replicated over IP to another DLm.

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