[T10] Operation of TAS bit related to Unit Attention

George Penokie george.penokie at avagotech.com
Tue Jan 26 10:20:53 PST 2016


Bill,

Well, they are both correct, it's just that SPC does not go into the
details that SAM has for this bit. Your quote from SAM is only one part of
the TAS bit behavior that relates to the Unit Attention which is not
technically a response to a specific command but a notification on the
response to a different command. The TAS bit relates to the specific
response to the command or commands that were aborted. If TAS is zero there
is no response to those aborted commands (but there is a Unit Attention
condition established). If TAS is one then each command that is aborted
gets a CC aborted command response.

So SAM has the details and they are correct. I'm not sure if SPC needs any
further clarification but if it does it should be small as I don't want
someone thinking they can understand how TAS works without reading SAM.

Bye for now,
George Penokie

Avago Technologies
Attn: George Penokie
4109 Manor View Dr NW
Rochester , MN 55901

952-921-2495
george.penokie at avagotech.com

On Tue, Jan 26, 2016 at 10:10 AM, Bill Martin-SSI <
bill.martin at ssi.samsung.com> wrote:

> Ralph & George:
>
>
>
> There is a conflict between SAM-5 and SPC-4 on the meaning of the TAS bit.
>
>
>
> SAM-5r21 states:
>
> If the TAS bit is set to zero in the Control mode page (see SPC-4), then
> the device server creates this unit attention condition for each I_T nexus
> that had command(s) aborted other than the I_T nexus that delivered the
> command. If the TAS bit is set to one in the Control mode page (see SPC-4),
> then the device server does not create this unit attention condition.
>
>
>
> SPC-4r08 states:
>
> A task aborted status (TAS) bit set to zero specifies that aborted
> commands shall be terminated by the device server without any response to
> the application client. A TAS bit set to one specifies that commands
> aborted by the actions of an I_T nexus other than the I_T nexus on which
> the command was received shall be completed with TASK ABORTED status (see
> SAM-5).
>
>
>
> Which was the intended meaning of this bit?
>
>
>
> Thanks,
>
>
>
> Bill Martin
>
> Vice Chair SNIA Technical Council
>
> Vice Chair INCITS T10
>
> SSD I/O Standards
>
> Samsung Semiconductor, Inc.
>
> Cell (408) 499-1839
>
>
>
>
>
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