I took a quick look at the code (not the RFC) and it I don't see anything special about LUN0 being the only LUN that can respond to REPORT_LUNS. Any LUN would work (assuming scsi_cmd_perform(...) is where all the action is). Wouldn't this mean that one would have to ensure to create at least a LUN0 (assuming the REPORT_LUNS isn't a LUN-less command (I'm SCSI-ignorant)). My suspicion is that the REPORT_LUNS command is a LUN-less command and would be responded to by the bus controller in the non-internet implementation of SCSI. Off to peruse the RFC. Dave -----Original Message----- From: ronnie sahlberg [mailto:ronniesahlberg@xxxxxxxxx] Sent: Wednesday, November 28, 2012 11:34 PM To: Braun, David Cc: stgt@xxxxxxxxxxxxxxx Subject: Re: Why LUN0? REPORTLUNS needs this. You must present a LUN 0 that can respond to REPORTLUNS so that an initiator can discover which LUNs are available. I think this is part of SAM for SCSI-3. Without a LUN:0 your initiator might either not be able to access any LUNs at all on your target, or if you are lucky/unlucky (I dont really know which, both options are highly undesireable) it might fall back to old style discovery and spin for many many minutes in a "try to talk to each LUN from LUN 0 to LUN <huge number> one at a time to see which ones exist" everytime you reboot and the host needs to re-scan the bus. regards ronnie sahlberg On Wed, Nov 28, 2012 at 5:53 PM, Braun, David <David.Braun@xxxxxxx> wrote: > I'm trying to understand the need for LUN0. Is this required by the > iSCSI standard (RFC-3720) or is it an artifact of the implementation? > As a test I modified a copy of tgtd and tgtadm to allow the "-force" > argument to the logicalunit delete function and it seems to work. BUT > I must confess I'm ignorant of what the ramifications could be. Could > someone explain the need for LUN0 or why I shouldn't be too surprised > when this hack blows up in my face? > > Thanks > > Dave > -- > To unsubscribe from this list: send the line "unsubscribe stgt" in the > body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
