[gentoo-user] testing a corrupt SD card

[Iain Buchanan <iaindb@netspace.net.au>]

Hi all,

recently my SD card just went bonkers.  Unfortunately I lost a lot of
photos on it (backups are useless until the data actually gets to the
backup...) but fortunately I was able to use a program to recover about
170 photos.

Anyway, I don't know if it was just static, shock, dead card, or phase
of the moon, so I would like to see if the card is good before I
continue to use it.

I've reformatted it and I get:
$ df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mmcblk0p1          500960    500960         0 100% /media/PICS

so I created a file:
dd if=/dev/urandom of=Desktop/random.img bs=1024 count=500960

then copied it to the card, and then copied it back as random-2.img.  If
I md5sum the two files, they are identical:
$ md5sum random*
9dcac25cfd8585be5939c0ff969de310  random-2.img
9dcac25cfd8585be5939c0ff969de310  random.img

Does that mean my memory card is good to go, or should I use some other
method of bad sector detection?

It's a Lexar Media 512Mb SD card, a couple of years old.  Yes I know I
can get a cheap 2Gb for <$20 but I'm more interested in the principle of
the test :)

thanks for any tips!
-- 
Iain Buchanan <iaindb at netspace dot net dot au>

This sentence contradicts itself -- no actually it doesn't.
		-- Douglas Hofstadter