IBM chooses MLC-based SSDs for its midrange, high-end arrays

Computerworld - IBM has selected STEC solid state drives (SSDs) based on consumer flash memory for use in its midrange and high-end storage arrays, the maker of SSD technologies for OEMs said today.

STEC said IBM has qualified their SSDs for use in its DS8800, DS8700 and Storwize 7000 storage systems, which were announced last month.

Through the use of virtualization technology, IBM's modular storage arrays can scale from 12 to 240 drives and incorporate capacity on the back-end from competing vendor arrays.

Today's announcement marks the first major reseller to adopt STEC's multi-level cell (MLC) SSD for use in a high-end storage system.

"This represents a lot of hard work put into introducing MLC SSD into high end storage media," said Scott Shadley, a technical marketing manager at STEC.

The IBM DS8800, DS8700 and Storwize V7000 are all equipped to optimize the use of SSDs with IBM's System Storage Easy Tier feature, which uses performance monitoring to move only the most active data to tier zero SSDs.

Traditionally, midrange and high-end storage system vendors have only used single-level cell (SLC) based flash memory because of its natively higher endurance. SLC NAND stores just one bit per cell versus two by MLC, which gives if vastly better endurance than the latter NAND flash technology. SLC typically can sustain 10 times the number of write-erase cycles as MLC NAND flash, giving about 100,000 write-erase cycles.

But while SLC performance is higher, so is its cost.

By using MLC-based SSDs, STEC can offer twice the capacity - up to 800GB per SSD - at 25% to 30% less cost, according to Shadley.

STEC is among a growing number of vendors who have adapted MLC flash for enterprise-class SSD products.

Last month, Israeli start-up Anobit Technologies announced Intel lead a group of investors who backed its MLC-based Genesis technology. OCZ, Pliant Technology, Samsung and Micron have also announced enterprise-class SSDs based on MLC NAND technology.

Enterprise MLC SSD, or eMLC as vendors now call it, uses less expensive flash memory but adds cache, special firmware for write amplification, error correction code (ECC) and the like, in the controller, and wear-leveling software in order to evenly spread data writes across the media to increase the reliability and performance of their products.

As the SSD software becomes more sophisticated, the reliability and performance levels of MLC-based drives are creeping closer to that of SLC-based products. Shadley said the company's ZuesIOPS MLC SSDs have the same five-year warranty as its SLC-based products.

The ZeusIOPS MLC drives, available in capacities of 600GB or 800GB, can handle intense workloads of up to 10 writes per day for over five years without limiting performance, the company said.

STEC's SLC-based SSDs are only offered with up to 400GB capacities.

STEC's ZeusIOPS MLC SSDs are available with a 6Gb Serial Attached SCSI (SAS) or 4Gb Fibre Channel interface.

The STEC eMLC-based SSDs use its CellCare bit management and Secure Array of Flash Element (S.A.F.E.) ECC technology to extend endurance and reliability.

"This type of collaboration effectively lowers the cost of SSD integration, without compromising performance, and paves the way for further SSD adoption across the enterprise." Manouch Moshayedi, STEC's CEO, said in a statement.

While STEC will place more emphasis on marketing MLC-based SSDs in the future, Shapley said its SLC-based flash products will not be obsolete anytime in the near future. The company will continue to carry those products for customers who request them for years to come, he said.

Lucas Mearian covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at @lucasmearian, or subscribe to Lucas's RSS feed . His e-mail address is lmearian@computerworld.com.

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