[CALUG] Can Media cards have bad blocks?

[Rajiv Gunja]

This would explain the past corruption of my CF and SD cards on Windows. I
just thought windows was crappy or I was messing something up. Good thing I
have my Photo Album (digikam) on my Linux PC.

As per the SD card being over-written, there is a small slider on the SD
card which locks the SD card from being written. I use it whenever I print
out pictures at a Kiosk.

Note: This months' Linux Format LXF131 has done a "Roundup" on Photo
Managers. Its a good read. If anyone needs that section, I can share the
PDF.

-GGR

--
Rajiv G Gunja
Blog: http://ossrocks.blogspot.com


On 9 April 2010 20:30, Bryan J Smith <b.j.smith at ieee.org> wrote:

> FYI, my warning prior was to those who might try to dd if=/dev/zero
> of=device, not that you did such.
>
> The BB command you utilized likely didn't wipe anything but a
> key block (like the root of FAT filesystem). All of your data
> is likely intact, just removed from any indexing from that key block.
> In general many devices can be picky on the format, and are best
> formatted by the device before use.  E.g., I only use my SDHC
> cards for my dSLR in my one dSLR brand/firmware and don't
> rotate them between other devices, other than for Linux
> to read. In fact, because Linux can do read-only mounts - while
> Windows can't - I always use such after seeing other people
> shoot and then Windows corrupt a FAT filesystem SD it didn't
> understand proper.
>
> It keeps me from getting burned at least.  Although anytime
> you start filling up a NAND device, expect failures shortly afterwards.
> It's especially frustrating for users when their device has
> reached the point where there are fewer blocks left that
> have not reached the failure tolerance than the device reports
> for allocation.  I've seen that many times myself, and it's funny
> to show the user with a vendor tool (rare these days, and most
> don't offer such tools now, every little off-shoot/whitebox
> SDHC, CF, USB, etc... NAND) that the device is only 70% usable
> from it's reported size.
>
> --
> Bryan J Smith - mailto:b.j.smith at ieee.org
> http://www.linkedin.com/in/bjsmith
> Sent via BlackBerry from T-Mobile
>
>
> -----Original Message-----
> From: "Bryan J Smith" <b.j.smith at ieee.org>
> Date: Fri, 9 Apr 2010 23:30:10
> To: James Ewing Cottrell 3rd<JECottrell3 at Comcast.NET>; <
> calug-bounces at unknownlamer.org>; Rajiv Gunja<opn.src.rocks at gmail.com>
> Cc: CALUG<calug at unknownlamer.org>
> Subject: Re: [CALUG] Can Media cards have bad blocks?
>
> All commodity NAND blocks have bad cells from virtually day 1.
> Within 1,000 writes, they will be unreliable.  These are the reality
> of the technology today.  They are also normally very slow at
> writes, but techniques are used to sychronize commits in the
> circuits.
> Access times are much better than disk, but still poor next
> to actual DRAM (let alone SRAM).  NAND != RAM, no matter how
> much people assume otherwise.
>
> --
> Bryan J Smith - mailto:b.j.smith at ieee.org
> http://www.linkedin.com/in/bjsmith
> Sent via BlackBerry from T-Mobile
>
>
> -----Original Message-----
> From: James Ewing Cottrell 3rd <JECottrell3 at Comcast.NET>
> Date: Fri, 09 Apr 2010 18:42:04
> To: Rajiv Gunja<opn.src.rocks at gmail.com>
> Cc: CALUG<calug at unknownlamer.org>
> Subject: Re: [CALUG] Can Media cards have bad blocks?
>
> If you asked me 8 days ago I would have said...
>
> No. Flash drive always record all data accurately.
>
> But the other 364 days a years....
>
> If a device can have Good Blocks, it can have Bad Blocks.
>
> JIM
>
> Rajiv Gunja wrote:
> > Hello,
> > I have been using my Mobile to listen to Music and Audio books rather
> > than carry around both my Mobile and iPod. The other advantage being, I
> > have a stereo bluetooth headset for my Mobile.
> >
> > On the media card 8GB MicroSD, There are folders created by my
> > BlackBerry. I have created couple of folders on them too, within the
> > directories it has created.
> >
> > Under Documents, I have created Audiobooks and eBooks. For some reason,
> > if I copy my MP3s to "Music" folder created by the BB OS, BB hangs and
> > becomes very slow and I have remove the SD card to make it respond.
> > Whereas if I copy those same MP3 files to "Audiobook" directory, it
> > works fine and plays fine too.
> >
> > Is this because there are bad block or whatever is holding the
> > information? Is it time to buy another card?
> >
> > -GGR
> >
> >
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