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    Re: Some questions about naming (newbie)



    > 3. A LUN WWN is at the SCSI LUN level, and can be used for identifying
    >    LUNs regardless of whether the underlying transport is FC, parallel
    >    SCSI, or iSCSI.  However, most FC devices do not support the LUN
    >    WWN, and use serial numbers, device IDs, and other mechanisms to
    >    correlate them.  To do this, one must implement device-type-specific
    >    code.

    > Anyway, those were just a few observations that might help.
    Thank you -- they do.

    > On question 3, keep in mind that an INQUIRY is done at the SCSI
    > level, and is independent of the SCSI transport mechanism used.
    > Therefore, the VPD information would not return anything that would
    > reflect an iSCSI identifier.  The ability to return a LUN WWN (from
    > (3) above) on this page really is a SCSI-level thing, and has nothing
    > to do with FC other than that it shares the same address format.
    I think i understand your point:
    A device might not be iSCSI only -- it might also have FC, plain SCSI
    (what's the official name for that?) interfaces, so the device doesn't
    necessarily know its node-name; that's the interface's responsibility?
    I don't actually need a node-name -- any identifying string will do.
    But the node-name is nice because the iSCSI naming spec requires it
    (along with the actual LUN number) to uniquely identify the LUN.
    That's something i don't know to be available through any other specifi-
    cation. Am i right there?

    > At any rate, in order to connect to a SCSI device via iSCSI to do
    > the INQUIRY, you must first log in to the target at the iSCSI level.
    > To do this, you would already have the iSCSI name (formerly WWUI),
    > so you should already have the information you need without the
    > inquiry data.
    Yes, but in order for my (application-level) code to do that, it has to be
    aware that the transport is iSCSI, and many OSs take great pains to hide
    that information from application-level code. MS even tries to make ATA
    hard disks look like SCSI (gag).
    So it would be nice if:

    1. Table 111 of the SCSI Primary Command set (T10 995d Rev. 11a)
       included an additional identifier type "iSCSI node-name"
    2. Devices supporting iSCSI were strongly recommended (even though
       this can't be required for the reasons discussed above) to report this
       identifier on VPD page 0x83.

    > Mark A. Bakke
    > Cisco Systems
    >
    mbakke@cisco.com
    > 763.398.1054

    Justin


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Last updated: Tue Sep 04 01:05:00 2001
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