[T10]Reset of a SCSI Target device
lohmeyer at t10.org
Thu Dec 5 09:48:29 PST 2002
* From the T10 Reflector (t10 at t10.org), posted by:
* John Lohmeyer <lohmeyer at t10.org>
Your target device is supposed to initiate another negotiation when the initiator next selects your device. Since targets are not allowed to originate a PPR negotiation, you must start with a WDTR or SDTR message. This will cause the initiator to notice that a PPR negotiation is needed. After it finishes the WDTR/SDTR negotiation, it will then initiate a PPR negotiation.
Why can't targets start with PPR? I forget the details, but it avoided some nasty error conditions. (Perhaps George Penokie remembers...)
By the way, a lot of old SCSI devices had vendor-specific disables to prevent targets from originating WDTR/SDTR negotiations because early SCSI initiators were implemented incorrectly. Note 7 in SPI-4 discusses this issue.
At 12/5/2002 02:37 PM, you wrote:
>* From the T10 Reflector (t10 at t10.org), posted by:
>* Petit Laurent <laurent.petit at barco.com>
>I am currently developing an external SCSI-3 target device and I wonder what
>to do in case of reset or power off/on of the device.
>My device supports PPR negotiation and is correctly detected at 160 MB/s by
>a Windows 2000 machine with an adaptec 39160 board. If I reset my device,
>the transfer parameters go back to the default mode which is narrow
>asynchronous. Is there any way to indicate to the initiator that my target
>has been resetted and thus that PPR negotiation has to be performed again ?
>What happens now is that the initiator issues an INQUIRY command expecting
>the data phase to be synchronous...
>Is there something specified in the SCSI standard indicating how the target
>should behave ?
>Thanks for your help,
>Rue du Bosquet 7 1348 Louvain-la-Neuve
>Tel: +32 - 10 - 45 49 04 Fax: +32 - 10 - 45 46 36
>Tel direct: +32 - 10 - 48 64 40
>laurent.petit at barco.com http://www.barco-silex.com
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John Lohmeyer Email: lohmeyer at t10.org
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