16 GB SD card (okay, SDHC really)

Discuss peripherals for the XO and power management.

Re: 16 GB SD card (okay, SDHC really)

Postby richf » Thu Mar 26, 2009 3:00 am

Newegg is now selling the A-Data Tubro 16GB, class 6 SDHC card for $29.


This looks like a pretty good deal, and it's now $28:

http://www.newegg.com/Product/Product.a ... 6820211245

And I like the idea that people here have reported good luck with it.

Although I am a bit concerned that this page benchmarked an 8GB A-Data card and found it poor with the XO:

http://ossguy.com/?p=27#A-Data

But I have no clue how much to correlate one A-Data card with another.

Anyone here have any performance problems?
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Re: 16 GB SD card (okay, SDHC really)

Postby grettke » Thu Mar 26, 2009 10:10 am

I didn't benchmark it but I can tell you that it works reliably in that the data never gets corruped and everything "just works".

I had used it for file storage but right now I have got Ubuntu 8.10 on it and it works well.
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Re: 16 GB SD card (okay, SDHC really)

Postby richf » Mon Apr 06, 2009 4:20 am

fwiw, instead of the A-Data I ended up buying the Patriot 16 GB Class 6 SD card.

I’ve only been at it one night so far (although it’s getting to be a long session), but so far I’m not having the best of luck booting from it (this is trying to install Ubuntu on it). For more info, see my posts in the following thread starting here:

http://www.olpcnews.com/forum/index.php ... 9#msg29589
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Re: 16 GB SD card (okay, SDHC really)

Postby grettke » Mon Apr 06, 2009 2:12 pm

richf wrote:fwiw, instead of the A-Data I ended up buying the Patriot 16 GB Class 6 SD card.

I’ve only been at it one night so far (although it’s getting to be a long session), but so far I’m not having the best of luck booting from it (this is trying to install Ubuntu on it). For more info, see my posts in the following thread starting here:

http://www.olpcnews.com/forum/index.php ... 9#msg29589


Stick at it. My XO will boot automatically off of the SD card about 50% of the time. The rest of the time it takes a manual boot at the forth prompt.
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Re: 16 GB SD card (okay, SDHC really)

Postby richf » Mon Apr 06, 2009 2:28 pm

grettke wrote:Stick at it. My XO will boot automatically off of the SD card about 50% of the time. The rest of the time it takes a manual boot at the forth prompt.


I fear I may have a more serious issue. I've had a fair number of reboots and manual boot attempts between last night and this morning, and still not a single success.

- Rich
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Re: 16 GB SD card (okay, SDHC really)

Postby ektoric » Mon Apr 06, 2009 6:20 pm

Since the XO's (linux's) SDHC driver is a reverse-engineered driver, it is more sensitive to vendors with varying interpretations of the spec. It is possible that your card indeed does not mesh well with the SDHC driver. If you are a kernel developer, I know that there are certain debug compile flags you can turn on to give a linux sdhc driver developers a better look at the problem and perhaps improve the driver.

A more practical solution may be to buy another brand. I previously had a Transcend 8gb which did not work out as well. Now I am currently using a Polaroid 8gb and it works much better.

In the mean time, have you tried this card on another system, perhaps your desktop system? Try re-fdisking and re-mkfsing it on a desktop system before putting it back into the XO.
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Re: 16 GB SD card (okay, SDHC really)

Postby richf » Tue Apr 07, 2009 3:20 am

ektoric wrote:Since the XO's (linux's) SDHC driver is a reverse-engineered driver, it is more sensitive to vendors with varying interpretations of the spec. It is possible that your card indeed does not mesh well with the SDHC driver.


The quick answer is that while it wasn't working with the q2e18 firmware, I was able to get things working by upgrading to q2e39. I have been able to install Ubuntu onto the SD card and boot from it, and I am in the process of the post-install updates.

In the mean time, have you tried this card on another system, perhaps your desktop system? Try re-fdisking and re-mkfsing it on a desktop system before putting it back into the XO.


Just to clarify, before upgrading the firmware, although I wasn't able to boot off of the SD card, in other respects as far as I could tell it was working okay, both on the XO and on other more conventional linux boxes. I was able to untar the Ubuntu distribution to it, I could see the files via both the SD slot on the XO and a USB card reader, the filesystem fsck'd okay, and the dir command at the OFW prompt on the XO *did* work for me, unlike the original poster in bug 9147 at https://dev.laptop.org/ticket/9147

- Rich
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Re: 16 GB SD card (okay, SDHC really)

Postby grettke » Tue Apr 07, 2009 9:46 am

The quick answer is that while it wasn't working with the q2e18 firmware, I was able to get things working by upgrading to q2e39. I have been able to install Ubuntu onto the SD card and boot from it, and I am in the process of the post-install updates.


That is great.

You know, the only strange thing is that on my system, some letters don't get rendered at all, and sometimes black triangle artifacts show up.
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