[linux-lvm] mount root filesystem on lvm

Manfred Gschweidl m.gschweidl at inode.at
Sun May 11 14:38:02 UTC 2003

Christophe Saout wrote:
> Am Son, 2003-05-11 um 20.00 schrieb Manfred Gschweidl:
>>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???
> When nobody created the /dev/control/mapper device on your root file
> system, it simply isn't there. ;-)

uupps...sorry, maybe i should carefully read my mails, after writing 
them. ;-)
i mean only one entry exists in "/dev/mapper", and this is "control", 
but no other entry.

> If you create it once it will stay there. "mknod /dev/mapper/control c
> 10 63" (or whatever the minor is, see cat /proc/misc)
> My linuxrc script creates this dynamically in the ramdisk based on
> /proc, but later you'll also need it on the root filesystem. Usually it
> is not necessary to do it on every reboot, because the filesystems isn't
> deleted between reboots, so creating it once should do it. You also
> shouldn't need to run a vgscan in the boot scripts because the known
> volume groups are cached in /etc between reboots, you can run it
> manually if something changes. Creating /dev/mapper/control once and
> adding vgchange -a y to the init scripts is ok.
>>cat /proc/devices show up, that there is still an entry for lvm, but 
>>also for device-mappper. is this maybe the error???
> No, I think they should coexist nicely.

thanks again,


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