Issues with 14-128r2: unmap clarifications

Gerry Houlder gerry.houlder at seagate.com
Mon Sep 8 11:48:13 PDT 2014


Attachment #1: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1409081_nameless-3636-2-1.html">nameless-3636-2-1.html</a>

I agree that this is adding a requirement that devices using logical block
provisioning are being strongly recommended (the "should") to unmap all
LBAs after sanitization, regardless of the sanitization type.
This is particularly bad for the sanitize overwrite case where the host is
specifying a sanitize pattern. If that pattern is non-zero, it is more
reasonable to presume that the host requires that pattern to be present
instead of the all zeros pattern that would be returned if the LBAs were
unmapped. This phrase seems to assume that devices that do provisioning
will not implement sanitize overwrite option, which could be a bad
assumption.
On Mon, Sep 8, 2014 at 1:09 PM, Nadesan Narenthiran <
Nadesan.Narenthiran at hgst.com> wrote:
>  Hi,
>
>
>
> The change at the top of page 3 for section 4.11.3 (completing a sanitize
> operation) is a new requirement on drives.  The proposed text says,
>
>
>
> the initial condition for every LBA should be anchored (see 4.7.3.2) or
> deallocated (see 4.7.3.3) (i.e.,
>
> LBAs that have been sanitized should be set to zero and autonomous LBA
> transitions (see 4.7.3.5)
>
> result in the LBAs becoming anchored or deallocated); and
>
>
>
> Currently a Cryptographic Sanitize operation is not required to set any
> particular value for the user data.  The host is only guaranteed consistent
> garbage data afterwards.  However this new text requires all zero data to
> be returned for the read command.  I think this part of the change should
> be clarified or struck.
>
>
>
>
>
> Someone with a better understanding on thin provisioned logical units
> should look at the middle of page 4 at the text
> For a thin provisioned logical unit (see 4.7.3.3) with the ANC_SUP bit
> set to zero in the Logical Block Provisioning
>
> VPD page (see 6.6.4):
>
> b) an ANCHOR bit set to one specifies that the device server shall
> terminate the command with CHECK
>
> CONDITION status with the sense key set to ILLEGAL REQUEST and the
> additional sense code set
>
> to INVALID FIELD IN CDB; and
>
> a) an ANCHOR bit set to zero specifies that any LBA on which an unmap
> operation is performed shall
>
> become deallocated.
>
> I am guessing that the wording on item a (second item on this list) should
> be a “should” and not a “shall”; Or that the wording should be a
copy of
> item a from the previous list.
>
>
>
> BTW, noting that item numbering needs to be corrected in a number of lists
> (example at above location).
>
>
>
> Have a nice day.
>
> Naren.
>



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