MOSAID Technologies has announced HLNAND2, a key step in the development of its innovative HLNAND (HyperLink NAND) Flash memory architecture and interface. Optimized for mass storage applications, including enterprise data centers and high-performance computing applications, HLNAND2 is the first NAND Flash interface that enables designers to easily achieve SSDs (Solid State Drives) with Gigabyte-per-second performance and Terabyte-class storage capacity. 

MOSAID's HLNAND (HyperLink NAND) Flash Memory Specification 2 utilizes a high-speed, point-to-point ring topology, facilitating the development of SSDs with data transfer rates into the multiple Gigabyte-per-second range. With a raw data rate of up to 800MB/s per channel, and 1600MB/s per channel with DuplexRW, HLNAND2 requires only one memory channel to reach a data transfer rate on the host interface exceeding 1 GB/s. In comparison, NAND Flash interfaces based on a parallel bus structure are limited to transfer rates of up to 200MB/s, with only a few devices supported on each channel. 

HLNAND's point-to-point interface creates an extremely clean signaling environment with reduced loading, allowing developers to build SSDs with Terabyte-class capacity without data-rate degradation. HLNAND's ring topology also eliminates the need for power hungry on-die termination that plagues variants of parallel-bus Flash.

"Solid State Drives that utilizes the HLNAND2 interface architecture can achieve an unequalled level of performance and flexibility," said Jin-Ki Kim, Vice President of R&D, MOSAID. "We expect to introduce HLNAND2 engineering samples later in 2011, enabling the design of HLNAND2 into a wide range of Flash storage applications requiring higher performance and scalability." 

Solving the interconnect challenge

There is a growing requirement for faster system interconnects to link storage systems in a wide variety of architectures to their computing infrastructure. Due to the severe limitations of NAND Flash interfaces based on a parallel bus structure, SSDs must be designed with large numbers of channels, in many cases distributed over several Flash controllers and interface chips. For example, in Enterprise systems, where the multilane PCIe interface is often used to connect storage hardware, SSDs require as many as 25 to 50 channels, connected to two or more SATA Flash controllers, an additional RAID controller, and a PCIe host bridge, to provide the throughput demanded by the system interconnect.

MOSAID's HLNAND Flash memory interface reduces the complexity of SSD design as interconnect speeds increase, while simultaneously increasing the capacity. Highly scalable, and with operating speeds closely matched to high-speed system interconnects, HLNAND offers a simpler approach to designing a wide variety of storage solutions without the scaling problems inherent with parallel busses. The HLNAND2 interface is closely matched to high-speed interconnects and therefore facilitates the development of a Flash controller with an integrated PCIe interface. This significantly reduces the need for parallelization of Flash channels and does away with the intermediate bridge devices. The result is a lower cost high-performance controller solution that is highly scalable and suitable for many applications.

HLNAND2 has an 8-bit, synchronous, DDR data bus but utilizes a source-synchronous clock and is, therefore, capable of operating at up to 400MHz to deliver up to 800MB/s of throughput. Other features include:

• Flash interface speed closely matched to high-speed system interconnects such as PCIe generations 2 and 3
• DuplexRW: Simultaneous DDR800 read & write, effectively 1600MB/s data throughput, well adapted to the PCIe duplexing feature
• Power saving by automatic packet truncation
• Built-in EDC (Error Detection Code) in 'Command Packets' for the best reliability in packet protocol communication.