Trying to decide which one ...

[P3R]

Hi forum,

My first post here, please be gentle.

The message so far seems to be that more than 512 MB RAM and 4 GB CF is a waste since it won't be used by the Meteohub application anyway. This lead me to some more questions.

Is the 256 MB RAM in the ALIX.1D also sufficient for Meteohub or will that cause any kind of performance penalty compared to the 512 MB boxes?

What CF cards are recommended? I have a 4 GB Sandisk Ultra II - would that be a waste to use in this application considering I can buy a slow no-name card for next to nothing and keep the Ultra II as my spare for photography, or would I even benefit from a faster card here like a Sandisk Extreme III or IV?

Would it be impossible to use the box for anything else concurrently with Meteohub and for that reason have a larger CF-card? I have some future low-CPU-stuff in mind that would be useful to have on the same box when I have the Meteohub well sorted out.

Thank you!

[sevenless]

I can't speak for the other portions of your question, but in regard to the brand of CF card you use, I'd recommend you stick with a name brand quality card. With the constant-on/constant-writing nature of Meteohub, too many of us have had cheap flash drives fail, resulting in lost time, lost data, and the added expense of purchasing another card. Given that the top-quality cards aren't much more than double the price of a generic knock-off, you'll probably end up spending more on multiple cheap CF cards than one quality one. However, you certainly don't need the SanDisk Extreme III or IV, because that sort of write speed is not an issue with this system.

And with that said, I'd still recommend backing up all the data daily, just in case!

[skyewright]

Is the 256 MB RAM in the ALIX.1D also sufficient for Meteohub or will that cause any kind of performance penalty compared to the 512 MB boxes?

I'm not a hardware expert, but the NSLU2 that was the only choice before the new platforms arrived has ony 32MB RAM and the ebox 2300, one of the original set of alternatives, has only 128MB RAM. If it is reasonable to compare like for like against those then 256MB RAM would seem at least to count as adequate...

[admin]

1) RAM:
256 is more than needed. I don't think that 512MB or more will have a positive impact.

2) CF card:
I would suggest a major brand, because I believe they have better wear-leveling algorithms in place. If you can get SLC based cards, this also is a plus, as these can handle 10 time the wear of standard MLC cells. To me the "Transcend Industrial Ultra 4GB" looks like a very fine SLC card. Other might work as well... time will tell.
Meteohub uses just the first 4GB, if a card is bigger, the spare will not be used, but can be a pro for wear-leveling, as the card has more unused cells to switch between. So if you get a 8GB for nearly the price of a 4 GB, take it.

3) Other applications:
My personal experience is that having weather data logging on a system I work with, install new code, test and program, then reliability of the logging will go down. But this is just my experience on how I behave on systems I am working with. I feel it being more appropriate for me, to have a separate weather logging unit, that just does this and is not bothered by my other it experiments.
As meteohub comes with it's own specialized linux distribution, not all packages you are planning to install on top might work, some might even interfere with Meteohub. I guess, only way to find out, is trying...

[P3R]

Great answer, thanks.

I've been able to find out that later Sandisk Ultra II cards are MLC (early ones are SLC) and realized that SLC is the best route to take.

Looking at the Transcend Industrial cards unfortunately gave me even more questions :)

What's the difference between part numbers TS4GCF100I and TS4GCF100I-P? I know the letter P stands for PIO-mode and that the first part number is said to be in UDMA-mode. But does that mean the cards can only do the respective mode or is it just the default and that they will switch if necessary? I've googled for many hours and haven't been able to find a definitive answer.

As far as I understand it UDMA-mode is preferable for speed but what does the ALIX.1D-board CF-interface use - PIO-mode, UDMA-mode or both? I find nothing about that in the specifications.

These things are probably obvious to the more hw-knowledgeable people but to me it's confusing and since the cards are very expensive I don't want to end up buying the wrong one. :unsure:

[admin]

To my knowledge ALIX.1D supports UDMA (at least it has UDMA settings in the BIOS) and I am not ware that the CF card socket can just be driven in PIO mode.

Hard to say, whether it is really necessary to buy an expansive SLC card. When you have the unit in your direct reach and backup data via rsync on a daily basis, a cheaper card may also do. As my x86 Meteohubs are just a few months old, I cannot report about personal experiences with cards dying. All look fine up to date, the cheap ones like the expansive cards. So it remains a bit of guess work, what the ultimate decision is.

[P3R]

I'll have the Meteohub at a remote location that I sometimes won't be able to physically access for several months so having the hardware as relaible as possible is important. Since the Transcend Ultra Industrial seems to be aimed at applications like this it is interesting, but I'll think it over for a while.

In case anybody else is interested I found this:
http://www.jacob-computer.de/_artnr_132693.html

Thank you!

[skyewright]

Does 4GB iCF 4000 Dual Channel Industrial Compact Flash - 266X look like a good CF card for an ALIX 1D?

[admin]

Hi,
all this is a bit of guess work, but from the details they give it looks ok. I don't know if it is SLC, but they advertise it having wear leveling, so I would expect long-term reliability being fine.

[skyewright]

all this is a bit of guess work, but from the details they give it looks ok.

That's pretty much the conclusion I came to - comparing specs. is hard when everyone seems to provide a different set of parameters and sometimes different terminology.

I'll probably give it a go. If so I'm sure you'll hear how it goes, either way... ;)

[P3R]

skyewright wrote:
I'll probably give it a go. If so I'm sure you'll hear how it goes, either way... ;)

I see in another thread that you have the ALIX.1D from the same supplier but did you choose the Innodisk CF-card?

[skyewright]

I see in another thread that you have the ALIX.1D from the same supplier but did you choose the Innodisk CF-card?

Yes.
It's only been installed and running for a few hours so far, so all I can really say at this point is that it seems to work just fine. :)

One thing I am intrigued to try (but may not get around to today) is to copy the data over from the NSLU2 on to the ALIX 1D, and then see how long a full recompute takes!

[admin]

you can use application data backup feature of your NSLU2 Meteohub, copy the resulting file "meteohub.backup" to the "/public" folger of the x86 Meteohub and then restore it from Meteohub's web interface. That will transfer all raw data, graphs, schedules and settings. You moght have to press save on a few pages (Sensors, WSWIN, WD, Graph Uploads).

[skyewright]

you can use application data backup feature of your NSLU2 Meteohub...

Will do, but the NSLU2 is doing a recomputation at present (I needed to change batteries in a sensor), so I'll at least wait till that has finished.

PS. While checking up on something in the manual I noticed "Depending on the amount of weather data to recompute this can take up to 20 minutes."

That seems a little, err, optimistic... ;)

... at least for an NSLU2 with a good quantity of data.

With less than a year's worth of data, the NSLU2 is currently taking quite a few hours (around 5 or so?) - though I suppose I do have quite a few sensors (2 "every 15 second" anemometers and 11 "around once a minute" other sensors).

[longtian006]

please let me know, how installation works out for you. What storage are you using? SSD?