Background operations and power loss expected

Gerry Houlder gerry.houlder at seagate.com
Fri Oct 7 06:31:10 PDT 2011


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1110071_f.htm">HTML-formatted message</a>

It seems like there are some contradictions among SAM-5 and SPC-4. This
should become an agenda item for the November CAP meeting.
On Fri, Oct 7, 2011 at 3:09 AM, Truong Nguyen - SISA <
tru.nguyen at sisa.samsung.com> wrote:
> Here is the representative text from SAM5r07 sub-clause 5.5:****
>
>  ****
>
> "Some commands initiate background operations that are processed after the
> command is no longer in the task set (i.e., status has been returned for
the
> command) (e.g., a SEND DIAGNOSTIC command when used to initiate a
background
> self-test (see SPC-4) or a write command when write cache is enabled (see
> SBC-3)). Background operations may be aborted by power on, hard reset, or
> logical unit reset. Background operations shall not be aborted by I_T nexus
> loss or power loss expected."****
>
>  ****
>
> The Send Diagnostic initiated background self test is described as an
> example of a "background operation" as defined by SAM-5. This is distinct
> from the "device specific background function" as defined in SPC4r32, which
> explicitly excludes the Send Diagnostic initiated background self test.***
> *
>
>  ****
>
> SAM5r07 defines "background operations" as follows:****
>
>  ****
>
> "*3.1.9 background operation: *An operation started by a command that
> continues processing after the command is no longer in the task set."****
>
>  ****
>
> This definition would seem to define a background operation as those
> initiated by the application client.****
>
>  ****
>
> Here is the relevant text from SPC4r32, with the power loss expected event
> handling introduced by 10-144r3:****
>
>  ****
>
> "An application client may request that a device server abort a self-test
> that is being performed in the background mode by sending a SEND DIAGNOSTIC
> command with the SELF-TEST CODE field set to 100b (i.e., abort background
> self-test function). A SCSI target device shall not abort a self-test being
> performed in the background mode as the result of an I_T nexus loss event
> (see SAM-4). A SCSI target device shall abort a self-test being performed
in
> the background mode as the result of a power loss expected event (see
> SAM-4)."****
>
>  ****
>
> 10-144r3 introduced the notion that a power loss expected event shall not
> abort the background self-test, which appears to conflict with SAM5r07 (and
> SAM4).****
>
>  ****
>
> Truong****
>
> ** **
> ------------------------------
>
> *From:* owner-t10 at t10.org [mailto:owner-t10 at t10.org] *On Behalf Of *Gerry
> Houlder
> *Sent:* Wednesday, October 05, 2011 11:15 AM
> *To:* T10 Reflector
> *Subject:* Re: Background operations and power loss expected****
>
> We tend to think of the device self-test that is kicked off via a SEND
> DIAGNOSTIC command to be a host initiated background task, whereas most
> other background tasks (e.g., background medium scan) are device initiated.
> I think this accounts for the conflict. ****
>
> ** **
>
> Perhaps SAM-5 should change wording to "Target device initiated background
> operations shall not be aborted ...". I think the SEND DIAGNOSTIC command
> case is the only host initiated background operation that is defined in
> SCSI.****
>
> On Wed, Oct 5, 2011 at 12:14 PM, Truong Nguyen - SISA <
> tru.nguyen at sisa.samsung.com> wrote:****
>
> In 10-144r3 (SPC:4 Self-test and SEND DIAGNOSTIC command clean-up), text
> was added to the Self-test operations Background mode model clause,
> specifying changes regarding power loss expected handling. Specifically, in
> sub-clause 5.8.4.3 Background mode (SPC-4r32), the following text was
added:
> ****
>
>  ****
>
> "A SCSI target device shall abort a self-test being performed in the
> background mode as the result of a power loss expected event (see SAM-4)."
> ****
>
> However, in SAM-4r14 (and in SAM-5r07), the following text is present in
> sub-clause 5.5 Command lifetime:****
>
> "Background operations shall not be aborted by I_T nexus loss or power loss
> expected."****
>
> When a power loss expected event occurs, which is the correct behaviour in
> terms of the background self-test? Should it be aborted or not be aborted?
> ****
>
>  ****
>
> Thanks,****
>
> Truong Nguyen****
>
> Samsung Information Systems****
>
> ** **
>



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