why would an SD card, after 12 hours, start to fail recording video?

why would an SD card, after 12 hours, start to fail recording video?

[Robert P. J. Day]

  a maddeningly vague question -- i'm currently after more information
-- but i've been told about an issue where someone is recording video
to an SD card and, after 12 hours, the units begin to "fail."  that's
all the info i have at the moment, i hope to get more so i don't even
know what the definition of "fail" is here, or the brands or models or
vendors involved, only what you read above.

  has anyone run across something like this before?  again, i realize
this is annoyingly vague but if i had a hint as to what might be
going on, i might be able to offer some advice.  what could possibly
cause properly recording SD cards to start misbehaving after several
hours?  thanks for any wildly speculative guesses.

rday

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
========================================================================

Re: why would an SD card, after 12 hours, start to fail recording video?

[Arnd Bergmann]

On Tuesday 24 May 2011 19:11:48 Robert P. J. Day wrote:
>   a maddeningly vague question -- i'm currently after more information
> -- but i've been told about an issue where someone is recording video
> to an SD card and, after 12 hours, the units begin to "fail."  that's
> all the info i have at the moment, i hope to get more so i don't even
> know what the definition of "fail" is here, or the brands or models or
> vendors involved, only what you read above.
> 
>   has anyone run across something like this before?  again, i realize
> this is annoyingly vague but if i had a hint as to what might be
> going on, i might be able to offer some advice.  what could possibly
> cause properly recording SD cards to start misbehaving after several
> hours?  thanks for any wildly speculative guesses.

There are many reasons why this could happen:

* You used a Kingston (or other cheap) SD card with a file system other
  than FAT32

* The partition is not aligned to 4 MB

* The cluster size is less than 16 KB

* You have multiple partitions on the card

If any of these are true, you have destroyed the card by writing a
lot of data to it.

	Arnd

Re: why would an SD card, after 12 hours, start to fail recording video?

[Robert P. J. Day]

On Tue, 24 May 2011, Arnd Bergmann wrote:

> On Tuesday 24 May 2011 19:11:48 Robert P. J. Day wrote:
> >   a maddeningly vague question -- i'm currently after more information
> > -- but i've been told about an issue where someone is recording video
> > to an SD card and, after 12 hours, the units begin to "fail."  that's
> > all the info i have at the moment, i hope to get more so i don't even
> > know what the definition of "fail" is here, or the brands or models or
> > vendors involved, only what you read above.
> >
> >   has anyone run across something like this before?  again, i realize
> > this is annoyingly vague but if i had a hint as to what might be
> > going on, i might be able to offer some advice.  what could possibly
> > cause properly recording SD cards to start misbehaving after several
> > hours?  thanks for any wildly speculative guesses.
>
> There are many reasons why this could happen:
>
> * You used a Kingston (or other cheap) SD card with a file system other
>   than FAT32
>
> * The partition is not aligned to 4 MB
>
> * The cluster size is less than 16 KB
>
> * You have multiple partitions on the card
>
> If any of these are true, you have destroyed the card by writing a
> lot of data to it.

  i'm not right this minute in a position to verify any of that but
here's a few more sentences i've received:

"What happens when the unit fails is that it stops recording suddenly.
There's no discernable pattern involved and no way to predict it."

and

"The error we see basically exhibits the following pattern:
- SD driver does not respond as expected to VFS
- FAT FS detects the error (FAT Panic) and remounts the device in read-only mode

"We also see numerous mildly corrupt FAT FSes during recording."

  once i get the detailed setup, i'll be able to verify any of the
above.  thanks muchly.

rday

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
========================================================================

RE: why would an SD card, after 12 hours, start to fail recording video?

[Patrick Fu]

Hi Arnd,

Arnd Bergmann wrote:
> On Tuesday 24 May 2011 19:11:48 Robert P. J. Day wrote:
> >   a maddeningly vague question -- i'm currently after more information
> > -- but i've been told about an issue where someone is recording video
> > to an SD card and, after 12 hours, the units begin to "fail."  that's
> > all the info i have at the moment, i hope to get more so i don't even
> > know what the definition of "fail" is here, or the brands or models or
> > vendors involved, only what you read above.
> >
> >   has anyone run across something like this before?  again, i realize
> > this is annoyingly vague but if i had a hint as to what might be going
> > on, i might be able to offer some advice.  what could possibly cause
> > properly recording SD cards to start misbehaving after several hours?
> > thanks for any wildly speculative guesses.
> 
> There are many reasons why this could happen:
> 
> * You used a Kingston (or other cheap) SD card with a file system other
>   than FAT32
> 

I'm just curious. How could this thing (file system type) affect read/write operations? 
Could you explain it a little?


Thanks,

Patrick

Re: why would an SD card, after 12 hours, start to fail recording video?

[Arnd Bergmann]

On Thursday 26 May 2011, Patrick Fu wrote:
> > There are many reasons why this could happen:
> > 
> > * You used a Kingston (or other cheap) SD card with a file system other
> >   than FAT32
> > 
> 
> I'm just curious. How could this thing (file system type) affect read/write operations? 
> Could you explain it a little?
> 
See my article at https://lwn.net/Articles/428584/ and the survey at https://wiki.linaro.org/WorkingGroups/Kernel/Projects/FlashCardSurvey.

Many cheap cards are designed for a very specific file system layout. If you
do something else, you can have orders of magnitude higher write amplification.

	Arnd