Wipe function on SSD's (nand flash)?

[Lawrence.1955]

yes. you can use ccleaner on all kinds of drives even flash drives and memory cards.

 

Hello,

What does Ccleaner write to wipe free space in "normal" and "secure, one pass" modes?

If one of these setting's writes ones to space reported "free" by the OS that will be very good.

 

As I understand it, writing " 1 " (ones's) to nand flash SSD's resets and "empties" the cell ready so it's ready to accept new writes directly. Only one "pass" is necessary for a reset.

 

However, writing " 0 " (zeroes) fills the cell with information that is retained which the controller then must remove in a separate operation before it can then write to the cell in a subsequent operation. Having to perform these two operations is what slows down writes on SSD's.

 

Which wipe mode writes "ones"? If neither do, can the wipe mode be set to write "ones".

 

Thanks

Lawrence

[DennisD]

Hi Lawrence, and welcome to Piriform.

 

Some relevant information here:

 

http://forum.piriform.com/index.php?showtopic=26285

 

Hope that helps.

 

 

EDIT: More info here:

 

http://forum.piriform.com/index.php?showto...st&p=160810

[Augeas]

The Write Free Space function writes one pass of zeroes. The Secure Delete function applies to files, not to WFS (in any event all of the secure delete options end with a pass of zeroes). Incidentally it is not possible to delete a file on an SSD securely by overwriting, due to the wear levelling process.

 

I understand that the wear levelling process on an SSD will distribute files across the drive until all space has been 'used' at least once. Then for subsequent writes the performance will drop as the SSD has to go into a read-erase-modify-write cycle, as it doesn't know which of the previously written blocks are still in use.

 

Possibly Lawrence would like to use CC to set all unused blocks to ones to indicate that the blocks are free. It's also possible that as CC's WFS process writes a number of large files to the device until all used space is taken up, and then deletes them, this will have the same effect as normal file write and deletion. In other words even if CC could WFS with ones it would be not be the same to the SSD as an empty unwritten block, and have no advantage at all.

 

It would be better to investigate a specialised TRIM utilty, if write performance is untenable. I believe that it's now incorporated in Win7. Even then TRIM will only operate on file deletions, not on file edit/saves.

 

(The usual caveat, que sais-je?)