Date: Fri, 21 Jul 2000 23:39:03 +0200 From: Wilko Bulte <wkb@freebie.demon.nl> To: Matthew Jacob <mjacob@feral.com> Cc: freebsd-arch@freebsd.org Subject: Re: How much do we need the all-singing, all-dancing devfs? Message-ID: <20000721233903.A21976@freebie.demon.nl> In-Reply-To: <Pine.BSF.4.05.10007211345470.8451-100000@semuta.feral.com>; from mjacob@feral.com on Fri, Jul 21, 2000 at 01:58:30PM -0700 References: <Pine.BSF.4.05.10007211345470.8451-100000@semuta.feral.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, Jul 21, 2000 at 01:58:30PM -0700, Matthew Jacob wrote: > 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 These are 64 bit WWNs. For example the CPQ HSGxx StorageWorks arrays present a 128 bit extended WWN for each of the LUNs they can present to the FC-AL/fabric they are connected to. A total of 128 LUNs can be presented via 2 host port pairs (a pair of ports acts as a failover pair in case one has redundant array controllers; of each controller one port is part of one pair). Serial numbers (IIRC) that are presented by a LUN are all the same: the ser# of the HSG raid controller. And are therefore quite useless to the problem at hand. So, I think it would be nice if 128 bit WWN could also be handled. A, very desirable IMO, side effect is that once this is done correctly one can use the information for use in a dual-rail driver. For HA systems having a dual connection to a RAID box becomes rather common these days. Using the WWNs it is relatively easy to spot multiple paths to a single LUN/disk. > 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. The problem I see is the fact that I have yet to meet someone who can correctly transcribe 64 bit numbers, let alone 128bit ones.. :-( But there is only so much you can do about that problem. W/ -- Wilko Bulte http://www.freebsd.org wilko@freebsd.org http://www.nlfug.nl To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20000721233903.A21976>