SAT TEST UNIT READY command translation
dougg at torque.net
Thu Aug 18 06:32:54 PDT 2005
* From the T10 Reflector (t10 at t10.org), posted by:
* Douglas Gilbert <dougg at torque.net>
"Sheffield, Robert L" <robert.l.sheffield at intel.com> wrote:
> This has the result that a SCSI logical unit represented by the
> SATL will never be in the STOPPED state. So, even though the SATL
> processed a START STOP UNIT command with START=0, the device as
> perceived by the SCSI application client will be in the SCSI
> STANDBY state. The response to TEST UNIT READY (assuming no
> errors) should be GOOD status.
That would be consistent.
I have made a small web page to summarize power conditions
(states) across several (draft) standards:
In the context of SAS there is another power condition (actually
two) to consider: ACTIVE_WAIT. For a SAS disk this is like the
STOPPED state. Media access commands are bounced with NOT READY:
LOGICAL UNIT NOT READY, NOTIFY (ENABLE SPINUP) REQUIRED. One
(or more) link layer NOTIFY (ENABLE SPINUP) primitives are
required (from an initiator or an expander) to transition the
SAS disk to ACTIVE power condition. A SAS transport can also
hold a SATA disk in a state similar to ACTIVE_WAIT. So if
there is a SAT layer in a SAS enclosure/expander how will this
new state be reported and transitioned?
> Question: does this cause problems for any SCSI applications
> - that a SAT logical unit will never go into the STOPPED state?
I don't think so.
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