Intel Atom Duo Core NAS

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General Technical Information

HOSTNAME	ATOM
SYSTEM CPU	Intel Atom 330 Duo Core @1600MHz
CACHE (2nd, 1st D/I)	512 KB per core, 24 KB / 32 KB per core
RAM	1 GB single channel DDR2 800MHz (Max. 2 GB)
IDE BUS	1 x ATA-100 (Max. 100 MB/s) 2 x Serial ATA2 (Max. 300 MB/s)
SCSI BUS	N/A
INTERFACES	6 x USB2 ports 1 x serial port 1 x parallell port
OPTION BUS	1 x PCI slot
GRAPHICS	Onboard Intel GMA950
DISPLAY	N/A (a monitor can be connected, but it's not needed for normal operation)
HARD DISK DRIVES	2 x 1.5 TB Western Digital Green Power, Serial ATA2 1 GB USB stick (Ubuntu Server boot + "/" device)
DVD DRIVE	N/A
FLOPPY DRIVE	N/A
NETWORK	10/100/1000baseT onboard ethernet
AUDIO	Onboard audio chip
OS	Ubuntu Server 8.04
YEAR	2009
SPEED	(not measured) VAX MIPS
POWER CONSUMPTION (MAX. / MEASURED)	100 / 48 W
COMMENTS	This computer is my home network mini file server. It can be remotely administered through a web interface.
PRICE '09 (Atom board, 2 x 1.5 TB disks, 1 GB RAM, Mini-ITX box)	$450

History and other comments

In the beginning of 2009 I decided to get some kind of NAS (Network Attached Storage) device. My criteria were something like this:

A lot of disk space >1TB
Possibility for RAID1 (mirroring) or another fail-safe solution.
Good performance (=should feel like a local disk)
Not too expensive

So more or less what everybody wants...

Okay, the first requirement is quite easy to fulfill. Most ready made NAS boxes have possibility for >1 TB of space, in 2009. For example the PPC based box from Excito looked interesting. Also the 2nd criteria, for redundant disks (no data loss, if one disk breaks) is indeed fulfilled by some boxes. But to my disappointment most cheaper boxes where equipped with only 100Mbps ethernet, which effectively would limit the data transfer rate to about 12MB/s. This is too slow for me.

At this point I was looking at the Synology boxes e.g. DS-209+ which has better features, and also good enough performance (in the "plus" models).

But at the time, it turned out that I couldn't get the Synology box with the disks I wanted. So I looked for other options. Then I happened to find comparisons of different NAS solutions at Smallnetbuilder, and found out that the Atom based MSI Wind PC would make a cheap and good solution. Unfortunately, this mini peecee was not available for sale as a barebone in Europe so then I figured out that it was time to build my own custom NAS with similar components, as in the Wind PC.

The Solution

I chose the D945GLCF2 Atom board from Intel, and disks from Western Digital (total of 3 TB, 2 x 1.5 TB). This Intel Mini-ITX board has all the needed features: a couple of Serial ATA2 connectors, suitable low power CPU and last but not least, Gigabit ethernet. Details are above. One interesting detail about this board is that operating systems running on it will recognise four discreet processors becuase of the 2 cores, each one supporting hyper-threading.

Software

Then the next step was to select the software. First I had a look at the FreeNAS project pages. This looked interesting, based on FreeBSD. Then I decided that I'd rather install a full featured server OS (but without graphical interface), so I selected Ubuntu Server. I used to run Ubuntu on in my previous firewall / server. Next, I installed Ubuntu Server on a USB stick (8.04 version installs without any extra tricks, on a USB stick) and now the board boots directly from the stick. No moving parts :-) well, except for the system fans on the board, and PSU of course.

Then I added mdadm for software RAID functions and Webmin (+ prerequisites, see instructions on Smallnetbuilder) for a free, very advanced web administration tool for Linux. This tool has more than enough features for a NAS.

Through Webmin I could then configure all the needed things on the Ubuntu Server for all the normal NAS functions such as partitioning the disks, setting up RAID1 / folder permisions and selecting network settings, adding needed file share folders etc.

Performance

With this NAS, I get a peak transfer rate of about 70MB/s, sustainable >60MB/s, copying files over Gigabit ethernet from my other peecee to the windows share located on the NAS' mirrored disks. This is a good number for a budget box like this, IMO. Other solutions with this kind of performance would be double the price (or more), as these usually include costly hot swappable disk cartridges, customised logic boards and proprietary software. This NAS is based on only free software and standard peecee components.

Simulating disk failure

Now the question is, how can I trust that my data is safe when there is no hardware RAID in my NAS? To be sure I would have to test what happens in case of an "allowed" failure:

One of the data disks breaks during operation.
One of the data disks doesn't operate anymore on startup.

These are the two cases where a RAID1 (mirroring) setup should protect 100% of the data.

(Please note that you will probably loose data if you should disconnect or break a disk during the time when the RAID1 partitions are resyncronising the data. On this NAS, the resyncing process takes about 4-5 hours, in a backbround process.)

The first case works as expected, I simulated this by removing the power cord from one of the disks during operation. After a minute or so, the software would detect the disk failure, and continue normal operation with a degraded array. No data loss, no problems after reboot. I could add the "failed" disk again without problems too.

The second case, however, caused some problems. Ubuntu Server dropped into single user mode complaining about the missing disk. Luckily by googling I could find the right commands to run to manually tell the RAID software that one of the disks has failed and it should continue to load the software, using the degraded array.

Please notice that each time you add a disk or restore a RAID array, the data needs to be resyncronised to all disks, so don't test this unless you are sure resyncing has finished.

So the conclusion is, basic tests passed. If something else in the NAS hardware breaks, then I could always pop in the disks in another peecee running Linux to access my data (this is something that may not be possible with proprietary NAS systems. If they are Linux based, maybe, if not who knows?).

Back to My Hardware Collection.

Last updated:

4-10-2009