| Re: Tagged Command Queuing |
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Group: microsoft.public.storage · Group Profile
Author: moojitmoojit Date: Mar 20, 2008 07:53
"KOOLER" rocketdivision.com> wrote in message
news:f2bdb21a-b32e-4cd0-9976-25681a92c7cc@m3g2000hsc.googlegroups.com...
Nonsense! For MS iSCSI initiator the only difference between "tagged
command queueing" enabled
or disabled is will it do serialization or not. If particular hard
disk drive reports it DOES support TGC
setting appropriate bit in it's SCSI inquiry data response then
initiator will NOT wait for command N
completion before sending command N+1 for execution. If device tells
it DOES NOT support TGC then
initiator WILL wait for command N to complete before sending command N
+1. Initiator does not generate
any commands itself, it simply receives full blown CDBs from upper
level driver in the stack (class driver
usually) and wraps CDBs into iSCSI PDUs.
Regards,
Anton Kolomyeytsev
CEO, Rocket Division Software
Per the Microsoft DDK, the QueueTag Field is assigned by the O/S specific
port driver. My interpretation is that the Class driver is not involved.
Moojit
On Mar 15, 5:31 pm, "moojit" moojit.net> wrote:> "mpoulos42" discussions.microsoft.com> wrote in message
>
> news:55D0C2FD-BC03-4598-B208-199D13628C74@microsoft.com...
>>> Thanks, but still need some clarification. Is theiSCSIinitiator a
>> "miniport" and does it support tagged commands?
>
> If you're using MS Initiator as a software initiator (using a standard NIC
> to talk to storage), then the MSiSCSIInitiator driver will generate tagged
> commands if needed. If you're using MS Initiator on a system that has a
> hardware HBA such as Qlogic's QLE4060, the STorport port driver and Qlogic
> miniport driver will determine if tagged commands will be generated.
>
> Moojit
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>> "moojit" wrote:
>
>>> Tagged commands are controlled by the port and miniport driver. The
>>> port
>>> driver determines when to use a tagged command but only if the miniport
>>> supports this functionality.
>
>>> Moojit
>>> "mpoulos42" discussions.microsoft.com> wrote in message
>>>news:C7202E83-36B8-41CA-8D43-40CC261BE368@microsoft.com...>>>> The Microsoft SCSI layer obviously supports Tagged Command Queuing.
>>>> However,
>>>> what is not clear is whether the MicrosoftiSCSIInitiator supports
>>>> sending
>>>> those settings over the wire to aniSCSItarget.
>
>>>> Does the implementation support ever sending commands with task
>>>> attributes
>>>> other than "untagged" over the wire?
>
>>>> And if so, what SCSI INQUIRY or MODE PAGE data is required to elicit
>>>> that
>>>> behavior from the Windows SCSI layer?- Hide quoted text -
>
> - Show quoted text -
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