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Linux-ready SoCs target consumer NAS devices

Jan 15, 2010 — by Eric Brown — from the LinuxDevices Archive — 89 views

PLX Technology announced a Linux-ready NAS 7800 system-on-a-chip (SoC) family for home network attached storage (NAS) devices. The low-end NAS 7820 and NAS 7821 and the high-end NAS 7825 offer dual ARM11 processors clocked to 750MHz, network security engines and a variety of hardware acceleration engines, says the company.

The NAS 7800 SoCs are based on technology acquired when PLX Technology purchased Oxford Semiconductor last January. PLX says the NAS 7800 family represents Oxford's third generation of consumer NAS SoC solutions. The company's chief line of business lies in PCI and PCIe bridges, switches, and processors.

Features supported by the PLX NAS 7800 family include basic NAS storage-sharing duties, plus high-speed streaming of high-definition video and high-resolution audio and photos, says the company. A Linux-based SDK (see farther below) is said to support connections to multiple computers, smartphones, digital photo frames (DPFs), Internet radio sites, and more.

According to PLX, the SDK also provides pre-developed applications that integrate NAS into set-top boxes (STBs) when using the NAS 7825. (As we'll explain below, this high-end part offers additional I/O designed for integrating NAS functionality in STBs, DVRs, and routers/gateways.)

NAS 7820/7821 architecture
(Click to enlarge)

PLX Technology claims to have doubled performance compared to the previous generation of NAS SoCs by implementing a new "Trident" architecture, which combines a dual-core ARM11 multi-processor with NAS application specific-hardware engines and software acceleration modules (see diagram below). Optimized acceleration functions include RAID, audio, VoIP and routing, says PLX. A hardware-based network security engine provides AES-128/256 bit-based encryption with hashing function support, the company adds.

Trident architecture
(Click to enlarge)

Hardware acceleration modules are said to include:

  • Gigabit Ethernet MAC with an TCP/IP offload engine (TOE) that transfers at Ethernet line rates
  • Eight-channel, low-latency buffered memory controller supporting DDR2 memory bandwidth bursts at 12Gbps
  • Eight DMA engines in multiple bus masters to transfer data without processor intervention
  • Internal SRAM memory for storing frequently used data
  • High-performance SATA controller with internal data buffers
  • Scatter/gather DMA controller, in-line encryption, and RAID functions

All three of the NAS 7800 SoCs clock their ARM cores to 750MHz, and they all share the same network co-processor, hardware acceleration engines, and a common 17 x 17mm 256 FBGA format. The SoCs also provide a 64b AXI multi-issue CPU bus architecture that enables numerous simultaneous transfers and data throughput bursts of up to 70Gbps, claims PLX.

All three SoCs support up to 512MB RAM, as well as SPI serial NOR flash, and SLC/MLC NAND flash, says PLX. The SoCs are said to offer dual USB 2.0 interfaces, as well as UART, SPI, I2C, and JTAG I/O. They also provide RGMII (reduced gigabit media independent interfaces) Ethernet connections, said to be required in secure router applications, as well as PCI Express interfaces.

The NAS 7820 and NAS 7821 are aimed at low-cost consumer NAS devices, and appear to be identical except that the 7821 offers two SATA interfaces instead of the 7820's one. Also, like the 7825 model, the 7821 SoC offers RAID support (RAID 0/1).

The high-end NAS 7825 is aimed at NAS-enabled routers/gateways, DVRs, and STBs, says the company (see architecture diagram below). The SoC offers dual PCIe 1.0 and dual RGMII connections instead of the single interfaces supplied by the 7820 and 7821, says PLX.

NAS 7825 architecture
(Click to enlarge)

NAS system boards incorporating the NAS 7800 SoCs do not require non-volatile memory, as the device's Linux firmware can boot from the disk drive, says PLX. The supplied software development kit (SDK) is said to offer full source code and script for the Linux kernel, boot-loader, root file system, and web pages. Additional SDK features include compilers, drivers, documentation, and a "complete turn-key solution," says the company.

The SDK also ships with a third party application environment for UPnP/DLNA media serving, content management, backup, remote management, and other NAS functions, says the company. Rapid Development Kits (RDKs), which include development boards and reference design schematics, are also said to be available.

Consumer NAS router/gateway reference design for NAS 7825
(Click to enlarge)

Stated David Raun, VP of marketing and business development at PLX, "All PLX storage devices are also backed by a comprehensive software/firmware package and an unmatched global technical support team that helps designers to differentiate their products and speed not just time to market but time to revenue."


General sampling and RDKs will be available for the NAS 7800 SoCs in the first quarter, followed by full production in Q2 2010, says PLX Technology. Volume unit pricing is said to be $15 for the NAS 7825, $13 for the NAS 7821 and $11 for the NAS 7820.

More information on the NAS 7820 and NAS 7821 may be found here and here, respectively. More on the NAS 7825 should be here.

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