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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: iSCSI: problem with LUN discoveryNelson Nahum, What I think you have said is that the accessing of the LUN information is OK the way it is today, you were proposing a standard way to get manufacturers to create the GUID, but that is not the responsibility of this group. In any event VPD page 83h is where Vendors Store that information as see by the initiators, regardless of the vendor chosen method of Long Term Storage of the ID. . . . John L. Hufferd "Nelson Nahum" <nnahum@store-age.com>@ece.cmu.edu on 10/04/2000 01:54:02 PM Sent by: owner-ips@ece.cmu.edu To: "Y P Cheng" <ycheng@advansys.com>, "'John Muth'" <muth@veritas.com>, <ips@ece.cmu.edu> cc: Subject: Re: iSCSI: problem with LUN discovery The question is if a storage controller keeps a different GUID for every LUN created. If not we are in the same problem as WWN, LUN naming. The question is how to identify a LUN in a storage controller that can create and delete thousands of LUNs, and that the same WWN, LUN combination can address different volumes depend on the intiator. Also to keep this identifier in the EEPROM of the controller is not a good idea, as cause problems when the controller is replaced. I think that the best way is to identify a LUN by a string composed by a <GUID> (or S/N) <date> and <time> of the LUN creation. This method allows to create infinite LUNs (over the time) in a given controller. Keeping this string in the media and presented it in a Inquiry page avoids the identification problems in controllers with multiple channels, that supports different mapping for multiple initiators. Nelson Nahum StoreAge ----- Original Message ----- From: Y P Cheng <ycheng@advansys.com> To: Nelson Nahum <NNahum@store-age.com>; 'John Muth' <muth@veritas.com>; <ips@ece.cmu.edu> Sent: Wednesday, October 04, 2000 9:01 PM Subject: RE: iSCSI: problem with LUN discovery > > -----Original Message----- > > From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of > > Nelson Nahum > > > > The problem is that the signature written by the VxVM is not standard and > > only is recognized by the Veritas VxVM. > > Due to the fact that the important thing is to identify the media not the > > controller (as Veritas does), the best way is to have the serial number > > written in the media in a non accessible sector, and loaded by the > > controller to one of the Inquiry pages of the LU. In this manner no matter > > which channel, WWN, LUN the specific LUN is presented can be > > recognized by every initiator. > > Every 1394 and Fibre Channel node, including disk drives, has a GUID, Global > Unique ID. They are saved in EEPROM by manufacturers. I believe T10 also > has a mechanism to report a unique name of a device using mode select. > (Page 83h? Someone help!) iSCSI should make sure that each device has a > GUID available by mode select for the initiators. No need to reinvent > another mechanism. > > > Y.P. Cheng, CTO, ConnectCom Solutions Corp.
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