On 01/24/2013 07:51 AM, Hannes Reinecke wrote: > On 01/24/2013 03:38 PM, Bart Van Assche wrote: >> On Thu, Jan 24, 2013 at 4:38 AM, Hannes Reinecke <hare@xxxxxxx> wrote: >>> As for AEN, does iSCSI _do_ AEN? I thought it got removed ... >>> >>> If it does, though, it should schedule an event on its own whenever >>> an AER >>> is received. The same goes for LLDDs with vendor-specific AENs; >>> thinking of >>> megaraid_sas here ... >> >> Let me ask this another way. SAN users expect that the LUN list at the >> initiator side gets updated automatically after a SAN configuration >> change. How should a SAN system communicate to a SCSI initiator that >> the LUN list has been changed ? Some FC SAN systems send a LIP after a >> configuration change to force the initiator to rescan LUNs. > > And thereby disrupting traffic on _ALL_ LUNs on the loop. > Really cool idea. > I know; the one vendor which does _not_ talk to us. > >> But how to inform the initiator about a LUN change for other SCSI >> protocols ? >> I'm not sure that it is even possible to report such a change via sense >> data in case a SAN user first removes all LUNs and after that change >> adds one or more LUNs. >> > The official way is indeed via UAs; most storage arrays (Hello, NetApp!) > provide a default LUN0 which is always visible. > Up to the point that some even refuse to add 'normal' disk LUNs to LUN0. > Or have the ominous 'Well-known Address' LUN to handle these kind of > issues. > > Obviously, one needs to send commands to it to even _get_ an UA back. > In SAM5 there is that QUERY ASYNCHRONOUS EVENT TMF. Could we send that periodically to lun0/well-knwon-lun if the transport supports it (iscsi will in http://tools.ietf.org/html/draft-ietf-storm-iscsi-sam-06#section-6). Whatever daemon in userspace handles these other events, could send it (we just need to add a interface) or we could add kernel code. This should not hold up Ewan's patches though. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
