| 1 |
* Francisco Ares <frares@×××××.com> [150730 15:53]: |
| 2 |
[..SNIP..} |
| 3 |
> Flash memory devices are tricky when you try do defrag, as there is extra |
| 4 |
> logic inside them to do the opposite: spread as much data as possible, as |
| 5 |
> to equalize the number of write operations - the main limit for flash |
| 6 |
> memory - for all sectors. |
| 7 |
> |
| 8 |
> Most defrag tools do this by reading files to RAM, reordering them, erasing |
| 9 |
> the originals from the media, then writing them again, using no direct |
| 10 |
> sector access, leaving that to the operating system. And it works on |
| 11 |
> magnetic media, as it creates empty spaces suitable for continuous files. |
| 12 |
> |
| 13 |
> So that extra logic may fool you, making you believe it worked, when it |
| 14 |
> didn't. |
| 15 |
> |
| 16 |
> Considering this, as already said, I would copy everything to another |
| 17 |
> media, set up a new partition layout, format the new partitions as desired, |
| 18 |
> then get all data back to the new layout. |
| 19 |
> |
| 20 |
> Just my 2 cents, of course. |
| 21 |
> |
| 22 |
> Good luck |
| 23 |
> Francisco |
| 24 |
|
| 25 |
I don't believe this is right (though I've been wrong before.) |
| 26 |
|
| 27 |
Both partitions and filesystems (including defragging filesystems) |
| 28 |
operate at the block level. |
| 29 |
|
| 30 |
Wear leveling and bad block handling happen "below" the block level. |
| 31 |
|
| 32 |
If you gave flash memory data for block n and later tried to read block |
| 33 |
n and got back something different it would be very broken. |
| 34 |
|
| 35 |
Of course physically logical block n might actually be stored in |
| 36 |
physical block y, but the flash controller (or whatever is responsible |
| 37 |
for wear leveling and bad block mapping) still needs to know to give |
| 38 |
back the data from physical block y when it's asked for logical block n. |
| 39 |
|
| 40 |
Todd |
Archives