TRIM utility

[Dimitry Andric]

On 24 Nov 2018, at 15:44, Wojciech Puchar <wojtek at puchar.net> wrote:
> 
>> Yes. It would. That's hard with the current storage stack to do via the
>> disk interface. And often the underlying protocols do not support partial
>> ranges. There is no good way to do this with buf/bio interface we have. So
> 
> what is an actual difference between "secure erase" and trimming whole disk?

It depends a lot on the device.  Some devices encrypt all blocks
automatically, and a Secure Erase command might just throw away the key,
not go over all the data and actively wipe it.

Most SSDs will likely also trim all the blocks to be erased, since users
have come to expect the SSD performance to go back to the 'out of box'
level, after such an operation.

If you are lucky, the manufacturer's documentation will explain the
specifics, but don't count on it. :)

-Dimitry

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