[Epic 4G General] rsage:
Very good theory, though I and others have noticed one thing that goes against it - some of the files were living and being used on the sdcard for quite a while before they got corrupted and moved to LOST.DIR. A couple examples: 1) I had listened to the affected mp3 several times before one day it suddenly cut off near the 1/2 way mark, after which I discovered the other half of the file was in LOST.DIR, and 2) I had used/read several other read-only files and sql lite db's numerous times before they suddenly no longer existed and were found in LOST.DIR (sometimes recoverable, sometimes not). When the latter happened, a zero byte file with the same name existed in the original file location, but the real file had been renamed as something like "567801" and moved to LOST.DIR. So it seems that when they were originally written to disk, the writes were successful.

Great information, thanks!

Possibly (and hopefully) you're right. Another possibility is that it's a more widespread issue, and users aren't realizing it for various reasons. Most of the corrupt/orphaned files I'm seeing in LOST.DIR wouldn't necessarily cause any overt symptom that anyone would notice - files like browser cache files, etc. It might not be noticeable to the user until a more important file is affected, and the issue may be dismissed out-of-hand or chalked up to some other more common issue usually fixed by clearing the data for a problematic app. One of the most common things I see on these boards is sudden and unexplained FC's of various apps, sometimes remedied by clearing data for the app, sometimes by reinstalling the app, and often users simply wipe all data and start over - never sure what the cause of the problem was. Every phone that's mentioned in various threads on this issue, or other android phones I've personally checked, have had LOST.DIR and LOST.DIR has never been empty. This seems to be true even if a specific phone wasn't having any issues that the user noticed. Obviously my sample size is very small, so I'm not saying this is universally true. But I think it's at least a possibility that the issue is more widespread and users may not be noticing it due to the nature of the affected files or maybe they're thinking it's some other problem.

I've also read a fair number of comments on this issue like "dude, wow I didn't know I had this directory but I do and there's 2gb of stuff in there!" Well, that 2gb of "stuff" had to come from somewhere ;)

Agreed, though this problem does seem to span many different brands/models of android devices (for those that have noticed the problem), so I'm thinking it's probably not my Epic. I'm hoping it's the card like you said. MicroSD cards aren't the most reliable storage media on the planet, so I'm really hoping it's just the card.

Agreed. Though I've had occasions when I've been testing and the files in LOST.DIR will increase without me really doing anything. In other words, I'll do a fresh boot of the phone, look in LOST.DIR with Root Explorer or ES and check the file count, then shut down the phone normally, wait a while, reboot normally, and there may be a few additional files in there. Of course there are always background processes running and probably accessing the card even if I'm not doing anything on the phone, so who knows. I've also rebooted the phone, checked the file count, properly mounted and unmounted the phone via USB on a Mac or PC, then checked the file count again just to see that there were a dozen new files in there. Good times...

mkasick - you seem very knowledgeable about the mechanics of reads/writes and internal android processes - do you think it's possible that the characteristics of certain ROM's, kernels, CW versions, or simply the act of flashing things all the time could have anything to do with this? I'm thinking not...