>>> On Tue, Jun 10, 2008 at 11:09 AM, in message <[EMAIL PROTECTED]>, Michael MacIsaac <[EMAIL PROTECTED]> wrote: -snip- > What strikes me as surprising is that it seems the disks "by-id" could not > be found after a power hit (I have no idea where to find the value > ccw-IBM.75000000030375.010b.22 in the above example). Why could the system > find the correct disk by name but not by ID? Has anyone experienced this? > (rebooting such systems has worked fine normally, so the power hit seems > to be related).
The uid comes from the storage device itself. From one of my z/VM guests: # cat /sys/bus/ccw/devices/0.0.0150/uid IBM.75000000026069.1014.16 It is supposed to be unique to the hardware device itself, based on serial number, or some such thing. If the actual hardware changes, so does that value. The "by-name" value gets generated by the Linux kernel, based on the order of the device numbers that get passed to it. That's why the names are not persistent, and can change if the kernel parameters are changed without preserving the original order. > Also, just a "heads-up" for anyone with SLES 10 SP1 and SP2. If you are > installing, you might want to click "Fstab Options" on the "Edit > Partition" panel and set the "Mount in /etc/fstab" radio button group to > "device name". If you have systems that identify disk by ID, you might > want to test scenarios such as this. Actually, you would be far better off using by-path instead, particularly in a z/VM environment, since it uses the actual (virtual) device number. >From that same Linux guest: # l -l /dev/disk/by-path/ total 0 drwxr-xr-x 2 root root 120 2008-06-09 11:16 ./ drwxr-xr-x 5 root root 100 2008-06-09 11:16 ../ lrwxrwxrwx 1 root root 11 2008-06-09 11:16 ccw-0.0.0150 -> ../../dasda lrwxrwxrwx 1 root root 12 2008-06-09 11:16 ccw-0.0.0150-part1 -> ../../dasda1 lrwxrwxrwx 1 root root 12 2008-06-09 11:16 ccw-0.0.0150-part2 -> ../../dasda2 lrwxrwxrwx 1 root root 12 2008-06-09 11:16 ccw-0.0.0150-part3 -> ../../dasda3 As long as the device number doesn't change, 0.0.0150 will always describe the same piece of disk, and if you clone a system and preserve the virtual device numbers, the new system will Just Work [tm]. Mark Post ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
