William Wong
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ED Online ID #21603 |
August 12, 2009
This iteration of Lab Bench Online takes a look at two different approaches to NAS and to embedded systems. The first is VIA Technologies ArTiGO A2000 (Fig. 1). This is a conventional NAS box that supports a pair of SATA drives. The second is Marvell’s SheevaPlug (Fig. 2). The SheevaPlug is designed for external USB drives. Both devices can handle any kind of USB device making them interesting development and deployment platforms for USB peripherals from data acquisition to printers.
The A2000 and SheevaPlug target developers and hobbyists but they are quite different in their target audiences. The A2000 is essentially a full x86 PC or server in disguise. The SheevaPlug is a low power, compact SoC-based system running the ARM architecture. Both will serve up files from a hard drive but the A2000 has the performance edge while the SheevaPlug is very flexible. The A2000 follows the more conventional NAS model while SheevaPlug has siblings like PogoPlug that use the same hardware base but add in an Internet-based backup and service distribution system.
From our perspective, the A2000 is a hardware project since it can be built up by adding some hardware and software. We’ll concentrate on construction here.
The SheevaPlug is more of a closed box albeit a system that can be expanded externally. The concentration here is the debugging and development tools.
ArTiGo A2000 VIA’s A2000 is a full fledge NAS server running a 1.5 GHz VIA C7 processor with a VX800 chipset complete with VGA output. This is on par with a low to mid range desktop and it can be used as such. There is just space for lots of storage. In this case, we crammed in 4 Tbytes using a pair of 2 Tbyte Seagate Barracuda LP drives (Fig. 3). There is some airspace under the drives but no fixed mounting points for additional boards. The system supports up to 2 Gybtes of DDR2 memory with a SO-DIMM single slot.
The front panel has status LEDs, the power button and a USB board. The rear panel (Fig. 4) provides access to the VGA port, audio outputs plus the 1 Gbit Ethernet port and a pair of USB ports. The USB ports can be used for additional storage, keyboards and mice, or any other USB device you care to try out. The interior is cramped with tight quarters for cabling. (Fig. 5) but the layout works as do the custom length SATA cables.
There is a large system cooling fan and the motherboard has its own fan on the heat sink. Overall, the system is very quiet especially when used with the quiet Seagate hard drives.
The system boots using a standard BIOS so it is possible to boot from one of the hard drives, the internal CompactFlash slot (Fig. 6), or a USB device such as a flash drive (Fig. 7). I actually used all three approaches.
The first step is popping open the system. There are three screws on the back and then it is possible to pop off the front panel. Installing the SO-DIMM takes patience because it is a tight fit but manageable. It is possible to do after the drives are installed but easier to see when they are not. The same is true for the WinSystems 1 Gbyte industrial CompactFlash I installed. That’s bigger than necessary for FreeNAS, one of the platforms used, but it provides enough space for a more substantial Linux installation. The two hard Seagate Barracuda LP hard drives were next. The SATA interfaces slide into the hard disk circuit board connectors. Four screws hold each drive in place. It was then a matter of popping the top back and plugging in the external power supply.
Elapsed time: fifteen minutes. It takes longer to unpack everything than assembling it.
Because of the arrival order of the hardware, my first pass did not include the CompactFlash card so I used a USB flash drive to install a server copy of Ubuntu. The system will easily handle a graphical interface and it is possible to run a remote console using VNC. There were no surprises and the system was essentially a PC.
Things got more interesting once the WinSystems CompactFlash card arrived. Adding it was easy but first I loaded it with FreeNAS. This is a free, open source, FreeBSD-based NAS server platform complete with an extensive web-based interface. It can run a host of file services from Samba (for Windows support) to NFS to SSH. The UPNP support can work with DLNA clients. It has SMART drive support as well as firewall support. Check out the website for all of the features and screen shots of the interface.
There are a number of advantages to using FreeNAS. First, it is a snap to install and use. Logic Supply, an ArTiGO A2000 distributor, has an image file that can be copied to the flash card for immediate booting. All that needs to be done is change passwords, set an IP address and setup the hard drives. The latest version of FreeNAS has the changes needed for the A2000 so the stock version is the way to go now.
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