Re: SD card robustness?
On Tue, Jun 14, 2011 at 03:15:59PM +0100, peter green wrote:
> I run debian on my beagleboard with the root filesystem on a SD
> card. Specifically a "sandisk for Wii" 2GB card. Recently the area
> surrounding the start of the ext3 root partition went bad nuking the
> superblock and thereby rendering the system unbootable.
>
> I managed to clone the card with gnu ddrescue and repair the
> filesystem using an alternate superblock so afaict I didn't really
> lose anything and I've replaced it with a sandisk 4GB SDHC card so
> the system is back up.
>
> However i'm worried it might happen again. Has anyone else seen
> similar issues running linux with root on SD card. Should I be
> buying something special and/or using a different filesystem? SD
> cards are supposed to have built in wear leveling right?
They should at least have some. Of course given that they are by spec
supposed to have a FAT filesystem (which variant depends on the size),
they are entirely allowed to choose to make the wear leveling more
advanced for the start of the card where the FAT table is stored since
it changes all the time, and not do any wear leveling on other parts
where only data is stored, since that would tend to be rewritten much
less often on cameras and other similar use cases. They could choose to
do no wear leveling at all, but then the card wouldn't last very long.
This doesn't mean some cheap cards don't take that route.
--
Len Sorensen
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