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Old Aug 30, 2009, 5:56 PM   #1
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Default 32Gb SDHC with bad sectors

I recently bought a generic 32Gb card on ebay http://cgi.ebay.com/NEW-32GB-SD-SDHC...d=p3286.c0.m14

and got what I paid for - a bunch of bad sectors which makes my recorded videos unplayable when it reaches a bad frame.

The actual fraction of bad blocks is pretty low ~ 0.001, but I can't get format to recognize them as bad. I tried using the badblocks program to detect them:

badblocks -b 512 -v -w /dev/mmcblk0p1 4296000 4096000
Checking for bad blocks in read-write mode
From block 4096000 to 4296000
Testing with pattern 0xaa: done
Reading and comparing: 4169376
4169377
4169378
4169379
...

After running the test twice on the same range of 200k 512byte blocks, I get about ~167 bad blocks, but the problem is that the block #s are different due to wear leveling, so I don't think the blocks can be marked bad at the file system level. The persistent # bad blocks suggests the card doesn't remap bad blocks, which would be a real bummer.

Is there anything I can do about them, or am I out of luck?
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Old Aug 30, 2009, 7:35 PM   #2
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Have you got Windows installed?

If so, I'd try this Panasonic SD Formatter utility and see if it can format it. It's my understanding that there are some differences in the way an SD card is supposed to be formatted. I don't know if it will run under wine or not.

http://panasonic.jp/support/global/c...formatter.html
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Old Aug 31, 2009, 1:29 AM   #3
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I have Vista, and I tried the Panasonic format tool with a full format (flash erase not supported, said yes to resize), but badblocks still reports ~ same # bad sectors

Interestingly, the beginning of the beginning 2gb of the drive seems error free. Maybe this "quality control" helps unsuspecting customers from noticing corrupt images and from totally ruining their reputation.

Meanwhile, I got an idea. I'll try creating a tool to write a file to claim all bad sectors. It will grow a file by writing patterns to every sector. If any read backs fail, that sector will be kept as part of the bad blocks file. Otherwise it will be freed. Stay tuned.
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Old Aug 31, 2009, 8:28 AM   #4
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I'd contact the vendor and ask for a replacement. If you have component problems, they can sometimes be impacted by things like temperature. For example, I used multiple passes of gnu ddrescue to get a good copy of an SD card a while back that worked better after it was hot. Sometimes, you see the opposite (work at cooler temperatures and begin to fail at higher temperatures).

From my perspective, it's really not worth the hassle to try and use a card with intermittent problems.
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Old Sep 16, 2009, 9:56 PM   #5
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Default Don't Risk memories

IMHO, throw away the card and get a branded, reliable card.

You may be able to isolate the bad sectors for now but you do not know if any will crop up in the future.

Don't risk the memories you have through the pictures and videos because of a cheap, unreliable memory card.

Try San Disk (very, very good reviews) or Kingston or some similar cards.
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Old Sep 18, 2009, 9:48 PM   #6
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also try transcend cards as well. If you look around the forum you will see that both myself and Jim C have some transcends and love them.........

dave
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Old Oct 8, 2009, 9:19 PM   #7
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It is a hacked SD card.... http://sosfakeflash.wordpress.com/
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Old Oct 12, 2009, 10:32 AM   #8
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Joe bought his card from xoldskool

http://sosfakeflash.wordpress.com/?s=xoldskool

Posted on August 22, 2009
xoldskool is an eBay seller of Counterfeit (Fake) Flash memory cards. xoldskool also sells mp players. Registered in Hong Kong, xoldskool is trying to hide his fraudulent activities with private auctions.
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Old May 4, 2011, 11:19 PM   #9
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Default Scammed me, too?

It looks like I may have gotten the same bad SD card on eBay. Bought a 32GB Kingston-branded SD card from seller "impressedshop" a few days ago with the same symptoms. All packaging was in Chinese and it was shipped from Hong Kong.

So beware!
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Old May 5, 2011, 1:19 PM   #10
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Well, at least in my case, the seller quickly just refunded the money. Didn't even offer to send another one. OK with me, though!
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