I'm having some really big problems with my N900, and am wondering if these could be overclocking/kernel-power v49 related.

The problem is that the opt partition becomes corrupted. A lot of badblocks according to dmesg. Reflashing the original firmware doesn't help. The problem occurs soon after again (And appears to become worse: re-occurs much sooner now than after my first reflash attempt).

I think it started around the time that I experimented a bit with:
- kernel-power v49 in extras-devel (with overclocked DSP profile).
- busybox-power.
- CSSU testing.
But I also dropped my N900 around the same time rather badly.
My N900 is also over 2 years old and heavily used (a lot of reflashing etc.), could it be just "normal" wear of the flash memory?

I will try to relocate the partitions on the internal MMC to avoid the bad blocks by connecting the N900 to my ubuntu desktop with backupmenu (USB mass storage mode), seems like the only possible solution to the problem. But other then that I'm out of ideas to solve it.

I think the most likely cause is either the drop of my n900 or wear of the flash memory, but would like to rule out negative effects of overclocking/kernel-power v49 a bit more.
Does anybody else have memory corruption problems after using kernel-power v49?
Do you agree that wear of the flash memory or physical damage (dropping the n900) is a more likely cause?

I also found a few other topics on TMO about similar problems:
http://talk.maemo.org/showthread.php?t=44203
http://talk.maemo.org/showthread.php?t=80717

I'm asking because I do have a second N900 to replace a possible defect device, but would like to make sure that that device lasts at least as long

Reflash eMMC + FIASCO?

Doesn't help. problem re-occurs soon after again.

Not likely to be related with overclocking, kernel power or other software. Just reasoning from my own experience and a lot of other power users I guess.

That's quite some statement...

How do you connect to which PC system???
Do you have any torrent application running?
Do you have any chroot, like EasyDebian, running?
Did you experience the same for an external microSD card?

Usually these steps help to get the file system intact again; you need rootsh installed to perform the code. There might happen an error for the umount command in line 2, if the partition is already unmounted, but you safely ignore this:

With other sotfware I was referring to the software Bernard mentioned:
- kernel-power v49 in extras-devel (with overclocked DSP profile).
- busybox-power.
- CSSU testing.

I was not entirely clear about that.

I connect to my Mint 9 computer (so that is Ubuntu Linux).
I experimented very little with transmission about a year ago, so no not running.
EasyDebian wasn't running either.
I have nitdroid installed on an external microSd card. That ran fine without any problems.
Soon after doing a fresh flash with the default maemo 5 images (both combined and eMMC) I get corruption in the blk0p2 partition (/opt).

I first decided to reflash because my N900 was becoming unstable (with KP v49, CSSU testing, busybox power etc. installed):
- spontaneous reboots
- file system gets loaded in read-only state because of bad blocks
- image files getting corrupted.

But after reflashing the problem didn't go away. In fact it seems worse (re-occurs sooner). I tried flashing with my own backupmenu image (with all the tweaks) and with the stock Maemo images.

Running a filesystem check using on blk0p2 using gparted on my linux desktop (by exporting the partition with backupmenu over USB mass storage) finds a lot of problems (and fixes them), but soon after I got badblock messages again.
(the check in backupmenu does something similar)

There is no advice i could give you from what you posted above. Given your experience with Linux and by the fact you used all the available tools to their extend... ,well, or not so well, some of those internal memory chips seem to deteriorate faster than others

I just hope that this permanent corruption isn't caused by overclocking or some bug in the new kernel-power v49 that I don't understand.
Otherwise I will kill my other N900 a lot sooner than I would like.

I still think I can get the problematic N900 in a functional state though. I think relocating the partitions (not using the first 2GB that probably have been used the most in the past 2 years), or doing a number of badblocks scans and marking all bad blocks I can find will probably do it. (or am I mistaken and does the N900 do some wear-leveling that spans the entire 32GB flash drive? Leveling wear even across partitions?)

If that does not help then there is definitely something else going very wrong (physical damage because of the dropping the device or overclocking?).

michaaa62 just pointed me to a possible similar case of a "read-only" flash MMC problem.
http://nourgomaa.com/my-nokia-n900-infected-chip/

It warns not to flash the device too often and not use backupmenu etc.
This seems very strange to me. The only thing what restoring an image in backupmenu does is formatting a flash partition and copying files. I don't see how that could cause any kind of physical damage.
And why a -R option in flasher would have any influence is also beyond me (it just tells the N900 to reset).

But I will open up the N900 if the relocation/badblock tagging doesn't work and find out if my N900 too has any kind of damage.