Could someone please merge those threads?

http://talk.maemo.org/showthread.php?t=49075
http://talk.maemo.org/showthread.php?t=42357

It's the same topic, the same discussion and the one thread has the other as information source.

Reading on microsd is always fast, no problem there. Writing is the issue.

Everything is for historical reasons optimized for harddrives, you take great care in placing everything in elaborate patterns on the drive, so that you can read it back with minimal seeking. You need to do exactly the opposite on flash, write everything sequentially because when reading back fragmentation doesn't really matter all that much...

The pattern on harddrives is like a gray-code 1213121412131215 is that what u want to try to say? Gray-code because it is the only code which differs exactly in 1-bit to the next code. Imagine u have a binary code there from 1 to 20 there u will see the code differs in more then 1-bit. I wonder what this ctorrent + flashlite patch do? How can it transform random writes in seq writes? It uses an AVL-tree but this alone wouldn't help?

No I don't mean gray codes.

I mean a HD is equally slow at read and write, and the theory is that you read more often than write, so the filesystem spends extra time to lay out the data during write.

MMC/SD flash drives are fast at reading, it doesn't matter much if files are extremely fragmented. However, they're slow at writing small fragments.