Messages in this thread | | | Subject | Re: [linux-usb-devel] Re: /proc/scsi/map | Date | Mon, 17 Jun 2002 11:42:05 -0500 | From | James Bottomley <> |
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patmans@us.ibm.com said: > I agree it would be nice to get the ID via user space, but it is not > that hard to get the ID, and trying the various SCSI INQUIRY pages > that supply the ID is not complicated.
OK, how about some hardware scenarios:
I've a scsi array (an LSI 6298) which has no WWN page (0x83) but does have a serial number in the VPD page. However, the VPD serial number is an identifier for the array *controller* and thus is the *same* for all the LUNs. For this beast I have to add in the LUN number to the VPD serial number to get a unique identifier per device. Worse, the LSI 6298 is multi path. Now I get a different "unique" identifier depending on path (because different controllers give different VPD serial numbers), so if I want to identify it uniquely, I have to use some property of the LUN, like partion UUID.
Or, what about an old 8 bit EMC symmetrix. They have no WWN page and they embed both a LUN and a *path* identifier in the VPD serial number. To get the globally unique ID for this one, I have to strip off the path part.
> FYI the various SCSI ID pages and such are described in the SCSI > primaray command for example the following:
> ftp://ftp.t10.org/t10/drafts/spc3/spc3r07.pdf
Ah, but that's the scsi-3 spec which (finally) cleaned up this unique name business. However, for SCSI-2 and before, it was an unholy mess, as the two examples above illustrate. I agree that for all modern devices which are SCSI-3 SPC compliant, then just asking for the WWN page probably works. The question is what to do about all the legacy hardware out there?
James
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