I was looking for some low level formatting tools and found this interesting piece of information:
http://sdprob.aximsite.com/

What is interesting is this part in particular:
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" And of course digital cameras, PDA's and 99% of the rest of the SD card devices need this "secure area" like you need another hole in your head. But guess what? You can't get it back. You can't format the "secure area" (Unless someone out there in webland knows of a consumer device that supports a low-level format) . Its under the control of the SD card's internal controller.

And guess what happens if the "secure area" becomes corrupted? Say bye-bye to your SD card... A high-level format can't directly access the secure area.

(Actually I'll admit the most common question is - why did my SD card go wrong? You should find the answer on the line above...)"
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So, most likely this reserved "Secure Area", present on all types of Secure Digital (SD) cards, might have been corrupted on permanently corrupted cards?

This begs to the question if anyone has had permanently corrupted MMC cards? AFAIK, MMC cards do not have this "Secure Area", since they do not have Digital Rights Management feature in them... Anyone messed up MMC card beyond repair on N800?

https://bugs.maemo.org/show_bug.cgi?id=1204
See Post #64
"However, the memory card slots in N800 have slightly different voltage regulation (max voltage and power), so it's possible that depending on the memory card the slots could behave slightly differently."

I can also imagine that they may have internal built-in controller firmware stored in flash and it becomes corrupted.Or something like this.When flash write is in progress and power is lost, with poorly designed internal hardware logic it could happen that internal flash programming logic fails miserably due to too low voltage and flash write can actually hit WRONG place.This is known reason of some firmware corruptions in microcontrollered devices where microcontroller IC has poor reset\brownout logic design.

Okay, take a look on scheme and please explain then how this happens and why, then.Both cards are attached to the same IC named "Menelaus" which does performs power regulations(this activity can be seen in dmesg log as well).It is pretty doubtful it has non-symmetric properties for same functional pins.So I guess electrical properties are near the same (plus or minus minor issues due to PCB layout).Of course corrections from Nokia staff are OK.Guy who posted this not seems to be Nokia staff.Or I'm wrong?

The internal slot has the capacity to provide a higher voltage than the external slot - as such, when the voltage drops perhaps the internal slot is still providing sufficient voltage to avoid any corruption because it was providing a higher voltage in the first place. The external slot on the other hand in a similar situation dips below the critical voltage threshold and card corruption is the result.

Post #64 is from a Nokia employee, and his comments are backed up by similar observations from the Linux kernel developer who originally added SDHC support.

External slot have wider range of voltages and is more fine grained so it can go lower. Check kernel source, it is there. I don't heve it here now but if card requests 2.8V it will get 2.9 (or maybe 3V?) in internal slot but 2.8 in external one.

After 2 years of Nokia's crap, isn't anyone else sick of being a beta tester. Its like QA doesn't even exist over there.

come on now penguinbait... witout nokia would you be porting kde/xfce for the latest palm/pocketpc

Nokia is not spoonfeeding... that would be akin to microsoft xp releasing a new powertoy... they are releasing much more than what we paid for.

This risk of great strides is a few stumbles. Without nokia i'd have a device that i like less than my 770, nevertheless 800.

They definately -should- put you guys on the payroll though

Has anyone managed to get a class 6 SDHC card to work? I purchased a class 6 8GB A-DATA to add to the class 2 I already have, thinking I'd get more speed. All I got was constant corruption of data, although thankfully it has yet to actually die. I've set it aside until things settle out or I may need eBay it since it may be a physical limitation of the n800. I did manage to make a class 4 8GB Patriot card work and I'm running it in the internal slot with the OS booting off of it to stress it and make sure it really works. No problems after several days and some forced ext2 fsck checks. Unless Nokia or the original kernel developer can make magic happen it looks like class 4 is the ceiling for cards.

Larry

Re: class 6 cards.

I'm using Kingston 8GB (class 6) SDHC cards in the internal slot of two different N800s. They are being uses as the root partion for each unit (as well as a FAT32 partion). I haven't had any trouble, and I have done large transfers over Wifi, as described, on both units. FWIW, before buying the cards I couldn't only find successful Kingston threads. Of course I could have missed some. Newegg has pretty good pricing.

I had a problem with my external SD card and was curropted showing in app. manager.

What i did is removed the card and put it in to my XtraDrive (turn your SD/ MMC memory cards into USB Thumb Drive) and turned it into USB Drive and pluged in to usb port and did low level format with HDD Low Level Format Tool 2.36.1181, may be letest version is there on website (HDDguru). After low level format i went in to manage by right clicking My Computer and formated with FAT32, removed USB drive and pluged SD back in to Slot and it was Working

Hope this may help someone