Date: Tue, 4 Nov 2008 12:47:33 +0100
From: =?utf-8?B?SsO2cm4=?= Engel <joern@logfs.org>
To: Pavel Machek <pavel@suse.cz>
Cc: kernel list <linux-kernel@vger.kernel.org>
Subject: Re: ext2/3 vs. kingston 32G SD card
Message-ID: <20081104114733.GA16036@logfs.org>
References: <20081104110225.GB4514@atrey.karlin.mff.cuni.cz>
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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
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