Date: Fri, 21 Jul 2000 13:58:30 -0700 (PDT) From: Matthew Jacob <mjacob@feral.com> To: freebsd-arch@freebsd.org Subject: How much do we need the all-singing, all-dancing devfs? Message-ID: <Pine.BSF.4.05.10007211345470.8451-100000@semuta.feral.com>
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It occurred to me that for at least what *I'm* interested in devfs for, that I may not actually need it. The portion I've always been interested in has been the location of unlabelled mass storage- disks. They can be known via VPD info (drive serial numbers) or via WWN (world wide names). Their physical bus 'address', particularly for Fibre Channel can change a lot, so the probe order in which they're seen causes them to show as differnt da units. We can guarantee that this won't change until a reboot (modulo the 'pack invalidation' issue- which is a separate issue). Given this, it's really a name translation issue to find out which da instance is which World Wide Name so and so. For example, I have: isp2: Target 0 (Loop 0x0) Port ID 0xef role Target arrived Port WWN 0x21000020370752ba Node WWN 0x20000020370752ba Which then probes as: pass9 at isp2 bus 0 target 0 lun 0 pass9: <SEAGATE ST19171FCSUN9.0G 1778> Fixed Direct Access SCSI-2 device pass9: Serial Number LAE84063 pass9: 100.000MB/s transfers, Tagged Queueing Enabled da6 at isp2 bus 0 target 0 lun 0 da6: <SEAGATE ST19171FCSUN9.0G 1778> Fixed Direct Access SCSI-2 device da6: Serial Number LAE84063 da6: 100.000MB/s transfers, Tagged Queueing Enabled da6: 8637MB (17689267 512 byte sectors: 255H 63S/T 1101C) It wouldn't be much extra work to be able to pass the WWN info up through CAM, so that, e.g., libcam, could fetch it. As a taste test, how would modifying mount to understand WWNs && serial numbers and do the appropriate translation to get the current 'da' instance number feel for people? This way, you might have something like fcwwn@0x21000020370752ba,0 / ufs rw 1 1 or scsidsn@"LAE84063",0 /space ufs rw 0 0 [ the trailing ',X' is a lun qualifier ] This way, we can really do SAN stuff *without* a full blown devfs. Thoughts? -matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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