Is SD solid enough as primary storage for file system in embedded system ?

5883 · 09-29-2012, 09:11 AM

used to use nand for linux fs in arm board, was ok,
now use SD, with ext2 fs, every once a while "cp some file" could case fs corruption.

this happened in multiple boards.

so is this the bad designing using SD as file system media,
or something wrong with the SD cards ?

any suggestions ?

JaseP · 09-29-2012, 11:32 AM

There might be several causes;

Could be...
SD quality,... The cards might not be rated fast enough for the file read/write operations

Firmware... The firmware might not support large file transfers (e.g.: some Android kernels)

SD card "spent"... All current SD cards,only support so many write operations before failing to be able to write any longer. Older cards support fewer writes than more modern cards with modern wear leveling techniques.

Or something else entirely, that I haven't thought of...

jefro · 09-29-2012, 04:30 PM

I'd think some power issue/power quality. Good case for cheap SD cards (cheap controller). Poor connections. EMI/RFI/poorly or ineffective shielding. Temps of system? Just because you have many boards it could still be that as fault or the OS. Wrong settings on how the SD is mounted or speeds or support like dma.

SD cards are used in millions of small systems.

In an odd way, some sd's could be too fast for some OS choices. Could easily be too slow.

Most of these board makers make claims based on some specs like the type and brand of SD even. Contact them maybe for their supported list.

I'd get a high quality SD and try it again.

onebuck · 09-30-2012, 10:16 AM

Moved: This thread is more suitable in <Linux-Embedded> and has been moved accordingly to help your thread/question get the exposure it deserves.

michaelk · 09-30-2012, 11:20 AM

Can you post the make/model of your arm board?
Do you perform a shutdown or just pull power to the board?

5883 · 09-30-2012, 01:27 PM

we build our own boards using at91sam9g45 in house,
no shutdown/power cycle, just normal mount/cp etc.

i'll grab more details tomorrow.
thx !

Quote:

Originally Posted by michaelk

Can you post the make/model of your arm board?
Do you perform a shutdown or just pull power to the board?