Yes...

-F

I'm going to add this thread to the bug tracker and see what I find out.

Tim

I've had cards that refuse to mount in the N800, the info bubble says "card is corrupt" but when I pop the card into a Windows XP card reader XP mounts it just fine with no hint of corruption. Interestingly, if I then insert the card back into the N800 the card is mounted without a problem.

It's as if something is being "corrupted" in the vfat filesystem which trips up the N800, and Windows will reset the "corruption" without a murmur. This suggests the N800/Linux vfat implementation is perhaps incomplete or over sensitive to some benign feature in the filesystem.

I have been suffering this memory card corruption issue too. Now lately my 4GB SD card that was working relatively good has become unusable.

I suspect the card is now bad because it does corrupt even when using with a PC USB card reader. I just copied a bunch of files to it and after that, without removing the card, I run disk check... and it found lots of errors and lost file fragments. Before it worked fine.

The question is that could it be that it has just wore out? I used to use that card with N800 and I had lots of MaemoMapper map files stored on it. I had formatted the card about 5 times total and copied the map files (over 20 thousand individual files) to it after each format... What I think that in that kind of use the FAT table (located in some certain memory address range) gets written each time any file is copied or deleted from the card. Once this is done some "tens of thousands times" it exceeds the life time of the memory cells located in the FAT table area.

This is just speculation from my part, but if there is someone who knows exactly how the FAT table updates are handled by the file system. Are all or some of those memory cells written each time any file change has happened?

Before I know for sure I'm not very confident starting to copy my map files to my new 8GB card... and destroy it... I'd rather use smaller and cheap card that I can afford to replace every once in a while... and use the big card for big and not frequently updated files only.

I did some research and looks like the FAT table flash wear out is very possible...
http://ej.iop.org/links/rSET_iM8K/Dh...nf6_48_248.pdf

Unless there is some built in wear out mechanism, the flash can easily wear out if the FAT table is updated frequently, such as when using Maemo Mapper.

Anybody have any more insight? Do (some/all?) SD cards have this wear out (load balancing) mechanism built in hardware, or is it the responsibility of SD card controller? Does N800 memory card controller has such code?

I'm pretty sure most (if not all) flash memory cards have built-in wear levelling these days - it's a feature built into the card itself so the controller/OS doesn't have to concern itself with this function, although some filesystems (such as jffs2 which is the filesystem used for the flash memory built into the 770/N800) are optimised to minimise updates where possible.

There is a discussion in bugzilla where a Nokia claims the flash memory in the device should be good for 30+ years assuming it is used every day. With a filesystem that is not optimised for flash it might be possible to assume that the lifetime of the card will be less than 30 years, but probably longer than a couple of years (which would be fine with me). I'll try and find a link...

EDIT: Bug #598 discusses wear levelling.

EDIT2: This wiki entry claims that SD and CF cards have built-in wear-levelling and error correction circuitry... no mention of MMC though.

FYI, all of my issues stemmed from brand new cards.

-T.

The last post in this thread appears old so maybe these problems are no longer occurring for most, but here's a recent similar experience. I've a Nokia N800 with the 128 mbyte card that came with it and a 6 gig SanDisk microSDHC. I had flashed OS2008 to it and was enjoying it when suddenly both cards borked with the same symptom. Apparently read-only without the ability to set or clear the read-only flag. These cards could be written on another machine with a USB SD card reader.

Taking another post advice I backed up a the 6 gig card and reformatted it with the N800. After that it said it was corrupt. The offered repair did not fix it. A reformat did not work. I removed it to another computer and it appeared fine. I reformatted it and wrote a bunch of files to it but it again said it was corrupt in the N800.

I finally REFLASHED 0S2008 and now all seems well again, the cards are again readable. Hope this was an isolated incident.

..prollymolly

Interesting. I just had a similar problem the other day with 'read-only' memory memory message for the card in the internal slot. I have a reg 4g sd in there.
By pure newb happenstance, I disabled the 'virtual memory' which I had at 128mbs and suddenly it was not an issue anymore.

Might that be a factor? Virtual memory?

Just my two cents worth.

Hello, sorry to be a newby, but I have excatly same problem with my 1gb sd in internal slot. Except that I have no extra virtual memory on my memory cards...