[linux-lvm] mount root filesystem on lvm

[Manfred Gschweidl]

hello again,

when i do a vgscan, i always get some messages like ...

SystemID universe1010067245 on /dev/md11 differs from universe1010064286 
for volume group

can anyone explain me, what this message means??? it seems that for all 
physical volumes, for which i get this message, the volume group, in 
which the pyhisical volume resides, cannot be activated.


thanks for any explanation in advance,


manfred




Manfred Gschweidl wrote:
> 
> hello and thanks for your help.
> 
> i modified my linuxrc file on the ramdisk, so that it does a "cat 
> /proc/devices" and "ls -l /dev/mapper". so i found out, that the device 
> number is also 254 and with the ls-comand i get the information that the 
> minor number was 6 (with the 2.4.12 kernel i couldn't find ot out, 
> because there i was not using the device-mapper interface).
> 
> after appending this to the new kernel on startup, the root filesystem 
> can now be found, and the system boots.
> 
> but now i have an problem... ;-)
> 
> when booting up with the initial ramdisk, and doing a "lvm vgscan" and 
> "lvm vgchange -a y", all volume groups and logical volumes are found 
> ("ls /dev/mapper" on the end of the linuxrc script shows all found 
> logical volumes).
> but after freeing memory of the initial ramdisk and mounting of the root 
> fs, now one of the entries in "/dev/mapper" exists, except the "control" 
> entry. and "lvm vgscan" and "lvm vgchange -a y" does not help. so i 
> cannot mount any other logical volumes?????
> the kernel complaines, that maybe a old kernel driver is using the 
> volume groups, but how can that be???
> 
> cat /proc/devices show up, that there is still an entry for lvm, but 
> also for device-mappper. is this maybe the error???
> 
> 
> if you can't help me out with this, this is no problem, because you 
> helped me a lot, since i can boot now...;-)
> but the "/usr", "/var".... directories are also residing on lvm volumes...
> 
> 
> thanks for your detailed help,
> 
> 
> manfred
> 
> 
> 
> 
> 
> 
> Christophe Saout wrote:
> 
>> Am Son, 2003-05-11 um 04.05 schrieb Manfred Gschweidl:
>>
>>
>>> when i use "/dev/progs/root" boot up ends with:
>>> VFS: Cannot open root device "3a00" or 3a:00
>>> Please append s correct "root=" boot option
>>> Kernel panic: VFS: Unable to mount root fs on 3a:00
>>
>>
>>
>> 0x3a is the LVM1 device major.
>>
>>
>>> when i use "/dev/mapper/progs-root" boot up ends with:
>>> VFS: Cannot open root device "mapper/progs-root" or 00:00
>>> Please append s correct "root=" boot option
>>> Kernel panic: VFS: Unable to mount root fs on 00:00
>>
>>
>>
>> Ok, 00:00 means that he didn't find anything there.
>>
>>
>>> i use the append option for "/dev/mapper/progs-root", because i can't 
>>> run lilo with it, because lilo says, that it doesn't find the device....
>>
>>
>>
>> Yep.
>>
>> It looks like you are currently running on LVM1 but want to switch to
>> LVM2 after the next reboot, right?
>>
>> LILO can only look at the device numbers currently in use in /dev, but
>> when there is no device-mapper device there, he can't find the device
>> number to use with LVM2.
>>
>> I don't think you can't activate a volume group at the same time with
>> LVM1 and LVM2, so you'll have to give it explicitly to the kernel
>> "command line" on the next reboot.
>>
>> Before reboot, can you find out what major device-mapper uses? Type "cat
>> /proc/devices" and search for the line with device-mapper. My kernel is
>> currently using the major 254, but I don't know if the numbers are
>> allocated the same way with the 2.4 kernel.
>>
>> Ok, then you'll have to translate the number to hexdecimal (e.g. using
>> this command line where you should replace 254 with your major number if
>> it differs: perl -e 'printf "%02x\n", 254).
>>
>> After rebooting you interrupt lilo and append root=##00 to the command
>> line, where ## is the major number in hex (so it looks like "linux
>> root=fe00"). If he doesn't find the root device, try fe01, fe02, etc...
>> until he finds the root device. The problem is that you can't know
>> exactly which minor number the kernel number will assign the volume
>> without having tested it first.
>>
>> This should of course only work when the ramdisk has correctly activated
>> the volume before the kernel tries to mount the root filesystem, there
>> should be a message printed.
>>
> 
> 
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