On Thu, Mar 15, 2007 at 02:19:11AM -0700, Steve Langasek wrote: > > Someone which uses scsi-over-fc have much better identification, the wwnn, > > which is used in by-id: > So it's used in by-id, but not in by-path, right? Hence this is still an > argument against by-path. No, similar identifiers are listed in both. And for s390 the initramfs scripts expects that the by-path name is used as root to be able to activate the complete device. > > | lrwxrwxrwx 1 root root 9 Mar 2 23:24 /dev/disk/by-id/scsi-320000020371a2f24 -> ../../sda > > | lrwxrwxrwx 1 root root 10 Mar 2 23:24 /dev/disk/by-id/scsi-320000020371a2f24-part1 -> ../../sda1 > > | lrwxrwxrwx 1 root root 10 Mar 2 23:24 /dev/disk/by-id/scsi-320000020371a2f24-part2 -> ../../sda2 320000020371a2f24 is the unique identifier of the disk. | lrwxrwxrwx 1 root root 9 Mar 2 23:24 ccw-0.0.2900-zfcp-0x21000020371a2f24:0x0000000000000000 -> ../../sda | lrwxrwxrwx 1 root root 10 Mar 2 23:24 ccw-0.0.2900-zfcp-0x21000020371a2f24:0x0000000000000000-part1 -> ../../sda1 | lrwxrwxrwx 1 root root 10 Mar 2 23:24 ccw-0.0.2900-zfcp-0x21000020371a2f24:0x0000000000000000-part2 -> ../../sda2 21000020371a2f24 is the identifier of the path to the disk. In this case there exists two paths to the disk via one controller. > > > Using dd to back up a partition to another isn't a very sensible backup > > > schema anyway. I think more people move PCI devices than back up systems > > > this way... > > It is widely used in form of snapshots. > Yes, snapshots are fairly common, and at least in the case of a power outage > / system crash you'd have to worry about them being around on reboot. Hmm, > having the system unable to mount a root fs at all on reboot would be even > worse for recovery than having it accidentally mount a snapshot, which is > already bad enough... But irrelevant in this case, as udev does not set links for dm devices in by-uuid, they have a unique name per definition. (Yes, two lvm vgs with the same name have weird effects ...) > Right. Do you think it would be sensible to rename both devices on > collision? Do you think that would be sufficient for making by-uuid a safe > default? I'm not sure. You always get a race condition between the events for the two devices. Bastian -- I have never understood the female capacity to avoid a direct answer to any question. -- Spock, "This Side of Paradise", stardate 3417.3
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