Re: ATA TRIM?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

[dholland]
> 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.

[RVP]
> OK, I've now actually looked at what the spec[1] says instead of
> relying on my faulty recall of stuff I read on lwn.net years ago.

> [1] [...]
> https://web.archive.org/web/20200616054353if_/http://t13.org/Documents/UploadedDocuments/docs2017/di529r18-ATAATAPI_Command_Set_-_4.pdf

According to that PDF, dholland is wrong.  PDF page 150, page-number
page 113, includes examples of "propperties associated with trimmed
logical sectors" including

a)  no storage resources; and
b)  read commands return:
    A)  a nondeterministic value that is independent of the previously written value;
    B)  a deterministic value that is independent of the previously written value; or
    C)  zero.

though it seems to me (b)(C) is actually a special case of (b)(B).  See
table 33, later on that page, for more.

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