ext2/3 vs. kingston 32G SD card

ext2/3 vs. kingston 32G SD card

[Pavel Machek]

Hi!

I got 32GB kingston SD card, and am using it with ext2 for storing git
trees etc.

Unfortunately, every time I run fsck, I get rather nasty corruption. 
I switched it to ext3 now, but I believe I have seen corruption even
on volume marked clean, which should be impossible from user error.

If I suspect wrong block device, what are useful tests to run there?

Or maybe I should do some test on filesystem level? (So far I try
compiling kernels, but that does not seem to provoke the corruption.)

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: ext2/3 vs. kingston 32G SD card

[Bart Van Assche]

On Tue, Nov 4, 2008 at 12:02 PM, Pavel Machek <pavel@suse.cz> wrote:
> If I suspect wrong block device, what are useful tests to run there?

Tools like xdd allow to write certain data patterns to a block device
and to verify the written data.

Bart.

Re: ext2/3 vs. kingston 32G SD card

[Jörn Engel]

On Tue, 4 November 2008 12:02:25 +0100, Pavel Machek wrote:
> 
> I got 32GB kingston SD card, and am using it with ext2 for storing git
> trees etc.
> 
> Unfortunately, every time I run fsck, I get rather nasty corruption. 
> I switched it to ext3 now, but I believe I have seen corruption even
> on volume marked clean, which should be impossible from user error.
> 
> If I suspect wrong block device, what are useful tests to run there?

Not likely in your case, but a number of counterfeited devices are on
the market.  They contain a much smaller chip inside than is advertised
plus some logic to return 0x00 when reading from non-existent memory.

To test for this, simply write 0xff to the complete device and read it
back.  'hd' is useful, as it compressed the output into four lines for a
good device and a bit more when you bought crap.

Jörn

-- 
Man darf nicht das, was uns unwahrscheinlich und unnatürlich erscheint,
mit dem verwechseln, was absolut unmöglich ist.
-- Carl Friedrich Gauß

Re: ext2/3 vs. kingston 32G SD card

[Pavel Machek]

> On Tue, 4 November 2008 12:02:25 +0100, Pavel Machek wrote:
> > 
> > I got 32GB kingston SD card, and am using it with ext2 for storing git
> > trees etc.
> > 
> > Unfortunately, every time I run fsck, I get rather nasty corruption. 
> > I switched it to ext3 now, but I believe I have seen corruption even
> > on volume marked clean, which should be impossible from user error.
> > 
> > If I suspect wrong block device, what are useful tests to run there?
> 
> Not likely in your case, but a number of counterfeited devices are on
> the market.  They contain a much smaller chip inside than is advertised
> plus some logic to return 0x00 when reading from non-existent memory.
> 
> To test for this, simply write 0xff to the complete device and read it
> back.  'hd' is useful, as it compressed the output into four lines for a
> good device and a bit more when you bought crap.

Ok, I switched to ext3 and the card seems to behave now. It seems to
hold the data, so it is probably not fake :-).
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html