<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html><head> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> </head>It's not similar to disk technology. In disk technology, sector<br/>write failures are in excess of 10**13, although it does not<br/>mean the sector has failed. In NAND technology, block failures<br/>are around 10**3, and a completely removed once a threshhold<br/>is reached. As such, block rotation is _mandatory_ with NAND,<br/>wholly unlike disk technology. In reliable design, this is done by the<br/>OS and filesystem (e.g., Linux JFFS2). But Windows doesn't<br/>offer such, so auto-rotated logic is provided by commodity<br/>devices.<br/><br/>Also, _never_ do a dd or complete block wipe. You _destroy_<br/>the longevity of the device. Again, most people shouldn't assume<br/>anything about commodity NAND, because it's wholly unlike<br/>anything they've ever dealt with. ;)<br/><p>-- <br/>Bryan J Smith - mailto:b.j.smith@ieee.org <br/>http://www.linkedin.com/in/bjsmith<br/>Sent via BlackBerry from T-Mobile <br/> </p><hr/><div><b>From: </b> Rajiv Gunja <opn.src.rocks@gmail.com>
</div><div><b>Date: </b>Fri, 9 Apr 2010 19:41:01 -0400</div><div><b>To: </b><b.j.smith@ieee.org></div><div><b>Cc: </b>James Ewing Cottrell 3rd<JECottrell3@comcast.net>; <calug-bounces@unknownlamer.org>; CALUG<calug@unknownlamer.org></div><div><b>Subject: </b>Re: [CALUG] Can Media cards have bad blocks?</div><div><br/></div><span style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">After confirming that there could be bad blocks, I erased all data from my 8 GB Micro-SD card and my mobile (using BlackBerry - wipe-device).</span><br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">
<span style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">Interestingly, I have no issues now on the memory card. Wonder if those bad blocks were remapped similar to the HDD remapping technology.</span><br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">
<br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;"><span style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">I am waiting for a good deal so I can buy a 16GB MicroSD card to replace it.</span><br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">
<br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;"><span style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">-GGR</span><br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;" clear="all">
<br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;"><span style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">--</span><br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;"><span style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">Rajiv G Gunja</span><br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">
<span style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">Blog: <a href="http://ossrocks.blogspot.com">http://ossrocks.blogspot.com</a></span><br style="color: rgb(0, 0, 153); font-family: verdana,sans-serif;">
<br><br><div class="gmail_quote">On 9 April 2010 19:30, Bryan J Smith <span dir="ltr"><<a href="mailto:b.j.smith@ieee.org">b.j.smith@ieee.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
All commodity NAND blocks have bad cells from virtually day 1.<br>
Within 1,000 writes, they will be unreliable. These are the reality<br>
of the technology today. They are also normally very slow at<br>
writes, but techniques are used to sychronize commits in the<br>
circuits.<br>
Access times are much better than disk, but still poor next<br>
to actual DRAM (let alone SRAM). NAND != RAM, no matter how<br>
much people assume otherwise.<br>
<br>
--<br>
<font color="#888888">Bryan J Smith - mailto:<a href="mailto:b.j.smith@ieee.org">b.j.smith@ieee.org</a><br>
<a href="http://www.linkedin.com/in/bjsmith" target="_blank">http://www.linkedin.com/in/bjsmith</a><br>
Sent via BlackBerry from T-Mobile<br>
</font><div><div></div><div class="h5"><br>
<br>
-----Original Message-----<br>
From: James Ewing Cottrell 3rd <JECottrell3@Comcast.NET><br>
Date: Fri, 09 Apr 2010 18:42:04<br>
To: Rajiv Gunja<<a href="mailto:opn.src.rocks@gmail.com">opn.src.rocks@gmail.com</a>><br>
Cc: CALUG<<a href="mailto:calug@unknownlamer.org">calug@unknownlamer.org</a>><br>
Subject: Re: [CALUG] Can Media cards have bad blocks?<br>
<br>
If you asked me 8 days ago I would have said...<br>
<br>
No. Flash drive always record all data accurately.<br>
<br>
But the other 364 days a years....<br>
<br>
If a device can have Good Blocks, it can have Bad Blocks.<br>
<br>
JIM<br>
<br>
Rajiv Gunja wrote:<br>
> Hello,<br>
> I have been using my Mobile to listen to Music and Audio books rather<br>
> than carry around both my Mobile and iPod. The other advantage being, I<br>
> have a stereo bluetooth headset for my Mobile.<br>
><br>
> On the media card 8GB MicroSD, There are folders created by my<br>
> BlackBerry. I have created couple of folders on them too, within the<br>
> directories it has created.<br>
><br>
> Under Documents, I have created Audiobooks and eBooks. For some reason,<br>
> if I copy my MP3s to "Music" folder created by the BB OS, BB hangs and<br>
> becomes very slow and I have remove the SD card to make it respond.<br>
> Whereas if I copy those same MP3 files to "Audiobook" directory, it<br>
> works fine and plays fine too.<br>
><br>
> Is this because there are bad block or whatever is holding the<br>
> information? Is it time to buy another card?<br>
><br>
> -GGR<br>
><br>
><br>
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