Re: ATA TRIM?

[David Holland <dholland-tech%netbsd.org@localhost>]

On Sun, Dec 25, 2022 at 10:27:49AM -0500, Mouse wrote:
 > >> According to that PDF, dholland is wrong.
 > > I fail to see a behaviour that would be allowed due to dholland@'s
 > > definition, but not according to the one you cited, nor the other way
 > > round.
 > 
 > A read returning the pre-TRIM contents.  Two of the options
 > specifically state "independent of the previously written value"; the
 > third is simply zero, which is also independent of the previously
 > written value.  dholland wrote
 > 
 > > The state of the data after TRIM is unspecified; you might read the
 > > old data, you might read zeros or ones, you might (I think) even read
 > > something else.
 > 
 > and, as I read that PDF, "you might read the old data" is specifically
 > disallowed.

I believe the drive is allowed to discard the request, in which case
you'll read the old data. I expect at that point the block is not
"trimmed" but ... that's a detail.

I know at least some drives will ignore single-sector trims.

-- 
David A. Holland
dholland%netbsd.org@localhost