Building my own NAS for DLNA (V): Conclusions

Time to do some maths. Let's call

• H the number of hours a week you stream content (on average),
• I the power consumption while idling,
• S the power consumption while streaming,
• C the cost in cents of a kWh,

you can estimate your annual costs by 0.00052 x C x [S x H+I x (168-H)] (evaluate your numbers). In my analysis, I'll take 21 as the weekly hours I stream content and 16 as the cents a kWh (euro or dollars, it doesn't matter for the maths):

• Atom netbook would cost me 9.95 a year (without VAT)
• Pentium M notebook would cost me 11.88 a year (without VAT) .

The difference is minimal. Both machines fit the requirements, but no one can choose for you. If you have an old notebook at hand , I think it is worth bringing back to life and using it as an very customizable DLNA/NAS unit, as you will only need an external USB disk to keep up with the storage requirements. But its battery probable will almost be destroyed because of the years (mine only lasts 5 minutes with a full recharge...), so it'll be only useful to avoid micro electrical shortages (as it sometimes happens in my building).

On the other hand, if you plan to buy you can find an old notebook for about €120 but I'd go for a new Atom netbook: it already comes with 1GB of RAM, the battery is fresh so you can take it with you when travelling and it will have more value after some years.

Don't hesitate in sharing your results/opinions in the comment section.

Building my own NAS for DLNA (I)
Building my own NAS for DLNA (II): specs
Building my own NAS for DLNA (III): performance
Building my own NAS for DLNA (IV): CPU usage and power consumption
Building my own NAS for DLNA (V): Conclusions

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Building my own NAS for DLNA (IV): CPU usage and power consumption

Well, seeing that streaming works fine on these two platforms, we should see how efficient they are. Serviio works by scanning the folders every 5 minutes (default, configurable value) and generating the data needed for future streaming in a TEMP directory. I suppose that in that way the job is ready when streaming starts. One problem I see with that approach is what happens if a scan starts with new files in the folders being processed while you're watching some content. The only thing I can say is that I still haven't had this issue.

CPU usage

To see how much CPU is used while scanning/preparing the files, I started Performance Monitor and Resource Monitor to check the general CPU usage and what processes were involved.

While idling, the CPU usage is between 4-5% in all cases, but transcoding changes it all. Serviio uses FFMPEG to do the actual work, and the problem is that this is not a multi-threaded process. This result in transcoding not consuming all CPU resources available in the Atom (2 logical cores), while the Pentium M (mono-core) reaches almost 100% CPU usage. Well, this has two consequences: first, the Atom could do other tasks while transcoding without suffering so much; second, as transcoding tend to scale very well with megahertz and/or CPU usage, we should expect shorter transcoding times in the Pentium M. While streaming the Atom consumes 5% more of CPU than the Pentium M.

I measure how long it took to transcode the two episodes of Top Gear (about 2.9 GB) in both machines, and the Atom one took 3 times as long as the Pentium M (400 seconds vs about 130).

Power consumption

The screen was open while testing, but when I closed it the consumption dropped 4 watts in the Pentium M and 1 watt in the Atom, an indicator of how efficient panels have become. As the PC will be headless most of the tim,e I'm using the values excluding this consumption.

The first thing to notice is that the Atom's consumption is below 2 watts, from idle to transcoding, while the Pentium M consumes 4 times the power while working hard. The fan also speeded up, making some noise. Streaming raises the consumption about 50% in the Pentium M.

Next (and last) chapter, conclusions.

Building my own NAS for DLNA (I)
Building my own NAS for DLNA (II): specs
Building my own NAS for DLNA (III): performance
Building my own NAS for DLNA (IV): CPU usage and power consumption
Building my own NAS for DLNA (V): Conclusions

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Building my own NAS for DLNA (III): performance

After introducing the test in part I, and comparing the specs of the two contenders in part II, let's do some benchmarks.

Test files

When I was setting up this test, I needed to use some HD big files, like on my very own usage. Some googling, and I found a 20 Mbps, MKV contained HD-DVD file (278.3 MB) and a fantastic collection of HD trailers from where I chose Sony's "Paint" (72.9 MB), one of the first I saw when this LCD era started. These two files add up to 352.64 MB.

I fancy watching Top Gear. In fact, it's the only TV show I wait for all week, and when a season ends... well, I can't wait for it to resume!!. So I have chosen a couple of episodes: Season 16, Episode 05 and Season 17, Episode 06, both 720p and about 1.45 GB each. I recommend you to use some kind of video you know in detail when testing, to see any difference. If you can almost say out loud the script of Matrix, that's the way to go! :-)

UPDATE: for those trying to absolutely squeeze your AV equipment, I recommend Samsung's "Oceanic Life": 40 Mbps of bitrate.

Network performance

I'm using my main PC and a Comtrend wifi router, both of them having gigabit ports. The problem is that the candidates have only Fast Ethernet ports, so we shouldn't expect lighting fast network speeds. In fact, the first thing to find out is raw network speed, without testing the hard drives. Jperf is a frontend for the Java based Iperf network speed app. It only needs to have Java JRE 1.5+ installed, and runs in server-client mode (you choose one of them) to max out the available bandwidth between them.

mmm, not very quick...

In fact, the differences are very small. The slowest one is Windows XP running on the Travelmate achieving 9.4 MB/s; switching to Windows Server 2003 makes it 8% faster, while the newer Aspire One is 12% faster. I told you, having 100Mbps interfaces won't make them very quick if you plan to copy very very big files.

I then time how long does it take to copy FROM (read test) and TO (write test) the "NAS". DiskBench is a free program that comes in handy. I copy twice one of Top Gear's episode, about 1.45 GB:

DiskBench is not a tool designed for everyday copying.

Mmm, it seems to me like the network limit is very close the machine's disks bottleneck. Travelmate wins when running Win 2K3 when reading, but it's always the loser when running Win XP.

I decided to do some more real life tests, as I'm not usually using DiskBenck for file copying. It's been years since I discovered CopyHandler, a replacement for the stock copying capabilities of Windows (cancel, resume, queueing and many more). Perhaps not the best of its class, but still very useful. It lets you even change the size of the buffer used when copying, so you can play a bit to adjust this parameter to fit your scenario. I copied over the 2 HD small videos (352.64 MB) three times, the average results are in MB/minute:

CopyHandler is a nice tool to use.

Increasing the buffer size from 128 kb to 2 Mb seems to work very well in all cases: when reading TravelMate under 2K3 is 10% faster and Aspire One 16%; when writing, TravelMate XP is about 5% and Aspire One about 12%.

Let's say we can achieve around a 500 MB/min performance with the TravelMate and about 450 MB/min with the Aspire One.

Streaming content

Then I started streaming content to see how much bandwidth is needed. It doesn't make any difference, as the results are almost the same while viewing one of the Top Gear's episode. You can monitor the network usage with the Performance Monitor in Windows, but to record average and max values, I've chosen another free little app, SoftPerfect NetWorks. You can even install the taskbar addon to monitor live bandwidth or start its speed meter to view max and average values:

• streaming (average): 600KB/s
• streaming (max): 1,55 MB/s
• streaming (initial maximun): 6,15 MB/s
• FF/RW skipping: 10 MB/s

The network usage is maximun when skipping the video (10 MB/s), up to the network's limit in my case as shown by JPerf. In fact, I noticed that skipping is faster when viewing the files using a directly attached USB stick. The second most demanding event is the start of the streaming (6,15 MB/s) perhaps while the player is buffering some seconds. After that, the average network usage is about 600 KB/s with some peaks at some scenes.

I think these results show that these machines are good enough to keep HD content streaming, as most of the hard work by Serviio is done when scanning the files, not while streaming them. We will see it in the next chapter (power consumption and CPU usage).

Building my own NAS for DLNA (I)
Building my own NAS for DLNA (II): specs
Building my own NAS for DLNA (III): performance
Building my own NAS for DLNA (IV): CPU usage and power consumption
Building my own NAS for DLNA (V): Conclusions

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Building my own NAS for DLNA (II): specs

On part I I explained what I'm trying to accomplish, and told you about a recent Atom netbook and an old Pentium M notebook. I also had at hand a Pentium 4 based notebook, but soon enough I realized that neither noise nor power consumption would be good, so I left it aside.

The netbook is an Acer Aspire One model AO751h. Based on a Atom Z520 1.33 Ghz processor, it has a good 11.6-inch WXGA 16:9 ratio Acer CrystalBrite High Definition LED back-lit TFT LCD (1364 x 768 resolution). The rest of the specs are the usual for this kind of netbooks.

The old notebook is an Acer Travelmate 382TCi and it dates back to the end of 2004/beginning of 2005, just upgraded to 1GB of memory. At the time, it was a business class ultra-portable notebook with a weight of just 1,6 kilos.


As you can see, the specs are very similar. The vertical screen resolution is the same (768), while the horizontal is better in the Aspire One thanks to its screen format. However, the Travelmate has a traditional 4:3 screen which some users find very useful.

Storage is won hands down by the netbook, but I don't think it is very important, as an external disk will be installed. Having bluetooth or webcam is a feature any user should value: BT lets you connect some keyboard/mouse combos, and the webcam will be useful if you want to do some videoconferencing.

The Aspire One has 3 USB 2.0 ports, while the Travelmate has only 2. But the later has a mini firewire connector, so if you are planning to use this kind of external storage it is great.


The Atom shows two logical cores thanks to hyper threading, and includes two newer instructions sets. The ancient Pentium M wins in raw clock speed and quadruples L2 cache size.

How do they perform? It looks to me like a neck and neck race. Let's find out...


Building my own NAS for DLNA (I)
Building my own NAS for DLNA (II): specs
Building my own NAS for DLNA (III): performance
Building my own NAS for DLNA (IV): CPU usage and power consumption
Building my own NAS for DLNA (V): Conclusions

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Building my own NAS for DLNA (I)

This year I finally bought a new TV and, after some research I chose a Samsung LE37C650 unit mainly for its networking capabilities and general good reviews out there.

From the beginning I streamed content from my main PC both in SD and HD. I started using the DLNA Server software Samsung offers, but it didn't work too well for me, so I started searching for something else. After some tests, I found Serviio worked very well, so it is my DLNA server since some months. It is great having a interesting and busy forum as well, and it seems to be an ongoing project. This software runs on Java, so it's multi-platform.

I soon realized that it would be a good idea to have a NAS on which to install this software so as to not having to switch on my main PC everytime, even though it is usually on. I bought a Western Digital My Book Live but I finally returned it: its DLNA server (Twonky Server version 5) was no up to date, and there were no free updates. And installing full Java for Serviio wasn't obvious...

Then I found some old equipment that I could evaluate as a DIY Advanced DLNA, and the obvious question was.. "How hard can it be?".

In this article I will evaluate an old Acer Travelmate 380 series powered with and old Pentium M class processor, and a not so old Acer Aspire One Atom based, to investigate their capabilities as an advanced DLNA platform. The unit should have:

• DLNA capabilities based on Serviio,
• NAS storage to home backups,
• Bittorrent and eMule download clients,
• Megaupload/Rapidshare/... downloading features,
• low energy consumption,
• remote access and management,
• low noise, and
  
• low cost.

In next chapter I'll introduce the specs of the tested computersto you. Stay tuned...

Building my own NAS for DLNA (I)
Building my own NAS for DLNA (II): specs
Building my own NAS for DLNA (III): performance
Building my own NAS for DLNA (IV): CPU usage and power consumption
Building my own NAS for DLNA (V): Conclusions


(Server image thanks to David Vignoni )

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Si te hemos sido útiles, ¿por qué no demostrar tu agradecimiento? Haz clic en alguno de nuestros anuncios, nos ayudarás a seguir con artículos como este.

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