On 02/08/2016 09:04 PM, Douglas Gilbert wrote: > On 16-02-08 02:00 PM, James Bottomley wrote: >> On Mon, 2016-02-08 at 12:33 -0500, Douglas Gilbert wrote: >>> Recently, in draft spc5r08, T10 added a locally assigned RFC 4122 >>> UUID *** designation descriptor. That descriptor can now be >>> returned for VPD page 0x83 (device identification) amongst others. >>> It can be used anywhere SCSI needs a unique identifier expanding >>> the previous set of preferred identifiers: EUI, NAA and SCSI_name >>> (iSCSI). >>> >>> In the soon to be released sg3_utils version 1.42 the new UUID >>> designation descriptor is decoded including Hannes' --export >>> option found in sg_inq, for example: >>> >>> # sg_inq --export /dev/sg0 >>> ... >>> SCSI_IDENT_LUN_UUID=11223344-5566-7788-aabb-ccddeeffffee >>> >>> Perhaps some udev work is needed to incorporate this new identifier. >> >> Hm, we're going to have to do this carefully. With the move to GPT >> partitions, both the UUID= designator in fstab and the /dev/disk/by >> -uuid/ of udev means the GPT UUID. In theory the design of the UUID >> space is to allow random selection without clashing, so we could just >> place the SCSI ones in here as well and perhaps there won't be a >> problem, but I'd like us to think about the consequences first. > > The UUID proposal (16-005r1 from Fred Knight and "Dr. Hannes Reinecke") > was somewhat controversial with five T10 members voting against it. The > minutes state: "The members voting no stated concern that this proposal > may result in market confusion, and those members intend to develop > proposals to mitigate any confusion." > > Locally assigned identifiers are not new: there already is an 8 byte > locally assigned NAA identifier (NAA=3). It is not much used, perhaps > the new locally assigned UUID (which is 16 bytes long) will find > more use. As for the 'sg_inq --export' naming, that seems to nail > down the context of the new UUID pretty well: > SCSI_IDENT_[TARGET|PORT|LUN]_UUID > with the identifier itself in canonical UUID format. So there should > be no confusion there. And partitions are nested inside logical > units and SCSI does not define those (apart from on tapes). > Precisely. These uuids will show up under /dev/disk/by-id (as this is a hardware ID coming from the device). So the existing UUID= or /dev/disk/by-uuid won't be influenced. And UUID handling is confusing already (with basically every subsystem providing one), so adding one more won't matter much :-) Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- 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
