Re: Do any SSDs support "erasing" a page?



On Tue, 15 Feb 2011 11:26:05 -0500, I (Mark F <mark53916@xxxxxxxxx>)
wrote:

Do any SSDs support erasing a page?

I want be able to erase a page on the SSD.

The purpose is to erase data in a page without
having to set an entire block to the programmable state.

A "page" is typically about 1 kilobyte, a "block" typically
about 512 kilobytes.

The SSD would have to understand that the page was no longer
in use once it was erased. The ECC would also be erased.
The SSD would use its usual algorithms for eventually re-initialing
the entire block and making it available for reuse.

The usual case is that if the file system view of the page is
"erased" the original page remains unchanged for an unknown period,
and could, with proper hardware, be retrieved at a later time.
Although my post that I am replying to here is recent, I have posted
about the issue in 2010. Now a group has made hardware to get at
the "raw" data on an SSD:
http://nvsl.ucsd.edu/sanitize/
"At the Non-volatile Systems Laboratory we have designed a procedure
to bypass the flash translation layer (FTL) on SSDs and directly
access the raw NAND flash chips to audit the success of any given
sanitization technique. Our results show that naïvely applying
techniques designed for sanitizing hard drives on SSDs, such as
overwriting and using built-in secure erase commands is unreliable
and sometimes results in all the data remaining intact. Furthermore,
our results also show that sanitizing single files on an SSD is much
more difficult than on a traditional hard drive. We are working on
designing new FTLs that correct these issues and also exploit
properties of flash memory to maintain performance while sanitizing
the flash drive. "

Also:
"For more information, please contact Dr. Steven Swanson
(swanson@xxxxxxxxxxx) or Michael Wei (mwei@xxxxxxxxxxx)."

Even data that was originally encrypted could usually be retrieved
if the original key was known.
.


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