Tagged Command Queuing - Storage

This is a discussion on Tagged Command Queuing - Storage ; The Microsoft SCSI layer obviously supports Tagged Command Queuing. However, what is not clear is whether the Microsoft iSCSI Initiator supports sending those settings over the wire to an iSCSI target. Does the implementation support ever sending commands with task ...

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Thread: Tagged Command Queuing

  1. Tagged Command Queuing

    The Microsoft SCSI layer obviously supports Tagged Command Queuing. However,
    what is not clear is whether the Microsoft iSCSI Initiator supports sending
    those settings over the wire to an iSCSI target.

    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?

  2. Re: Tagged Command Queuing

    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" 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 Microsoft iSCSI Initiator supports
    > sending
    > those settings over the wire to an iSCSI target.
    >
    > 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?




  3. Re: Tagged Command Queuing

    Thanks, but still need some clarification. Is the iSCSI initiator a
    "miniport" and does it support tagged commands?

    "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" 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 Microsoft iSCSI Initiator supports
    > > sending
    > > those settings over the wire to an iSCSI target.
    > >
    > > 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?

    >
    >
    >


  4. Re: Tagged Command Queuing


    "mpoulos42" wrote in message
    news:55D0C2FD-BC03-4598-B208-199D13628C74@microsoft.com...
    > Thanks, but still need some clarification. Is the iSCSI initiator 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 MS iSCSI Initiator 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


    >
    > "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" 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 Microsoft iSCSI Initiator supports
    >> > sending
    >> > those settings over the wire to an iSCSI target.
    >> >
    >> > 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?

    >>
    >>
    >>




  5. Re: Tagged Command Queuing

    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

    On Mar 15, 5:31*pm, "moojit" wrote:
    > "mpoulos42" 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
    >
    >
    >
    >
    >
    > > "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" 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 -



  6. Re: Tagged Command Queuing


    "KOOLER" 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" wrote:
    > "mpoulos42" 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
    >
    >
    >
    >
    >
    > > "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" 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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