Pliant delivers EFD SSD drives

Posted on September 14, 2009

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By Dave Simpson

-- Startup Pliant Technology today announced its entry into the solid-state disk (SSD) fray with the introduction of its Lightning line of Enterprise Flash Drives (EFDs). The drives are designed for OEMs and integrators building hybrid arrays consisting of SSDs and traditional hard disk drives (HDDs).

According to Jim Handy, director of the Objective Analysis research and consulting firm (which specializes in the SSD market), one differentiator for Pliant is that its EFDs are based on the SAS interface, which is relatively rare in the SSD market.

The drives are expected to compete primarily with SSD drives from STEC, which has the lion's share of the OEM market for SSD drives. Although STEC has been focused primarily on Fibre Channel-based SSDs, the company does sell 3Gbps SAS versions of its ZeusIOPS SSDs and is expected to begin production shipments of 6Gbps SAS versions by the end of the year. Pliant's Lightning EFDs are based on the 3Gbps SAS interface.

EFDs are also expected to compete to a degree with SSDs from Intel, although some analysts – such as Objective Analysis' Handy – do not consider Intel's SATA-based  (single-port, half-duplex) X25-E SSDs to be "enterprise class" SSDs. (SAS drives are dual-port, full-duplex devices.)

EFD SSDs are based on single-level cell (SLC) NAND flash modules from Samsung. Pliant's value-add lies largely in its software and a custom ASIC controller.

The software is designed to mitigate the inherent drawbacks to NAND flash technology by providing a number of reliability features, including triple-redundant (three copies) ECC-protected metadata and background Patrol Read and Memory Reclaim functionality. The Patrol Read feature is aimed at mitigating the "read disturbs" issue with NAND flash technology.

According to Greg Goelz, Pliant's vice president of marketing, there are no restrictions on the number of writes over the lifetime of the media.

EFD SSDs also support multiple sector sizes (512, 520 and 528 bytes per sector), and do not depend on a write cache for performance. The cache-less design prevents data loss in the event of power interruptions.

In addition, Objective Analysis' Handy says that the absence of DRAM in the EFD SSDs could be a differentiator for Pliant. "It's very difficult to build a high-performance SSD without DRAM, and that could be a real plus for Pliant," says Handy.

Pliant's custom ASIC handles all control functions, including I/O management, error correction, command structures, and data transfers to/from flash memory.

The Lightning EFD drives are available in 3.5-inch LS models (150GB or 300GB) and 2.5-inch LB models (150GB).

On the LS model, Pliant claims performance of more than 160,000 I/Os per second (IOPS) and a read/write sustained data transfer rate of more than 525/340MBps. With a 70/30 read/write ratio with 4KB transfers, the company claims more than 80,000 IOPS in a dual-port configuration. And in a typical enterprise profile workload ranging from read/write ratios of 90/10 to 60/40, Pliant claims performance of more than 32,000 IOPS in a single-port configuration with a queue depth of 64.

Pliant did not reveal pricing information on the EFD drives, which will be established by the company's OEMs.

Related articles:
Adaptec enables SSD + HDD RAID
Product highlights from the Flash Memory Summit
SSDs require new array architectures


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