[linux-lvm] mount root filesystem on lvm

[linux-lvm] mount root filesystem on lvm

[Manfred Gschweidl]

hello again,

now i solved the problems with "/dev/mapper/control".

it seems, that the kernel now finds all volumegroups, but now i get a 
kernel panic, that the kernel cannot mount my root filesystem within the 
lvm volumes. the message says, that i should append the correct "root=" 
boot option on startup??

with kernel 2.4.12 and lvm 1.x it was "/dev/progs/root".
now i use kernel 2.4.20 with device-mapper and lvm2.
as with kernel 2.4.12 i use a inital ramdisk.

how can i find out, what now is the correct option for "root="??


thanks for any help again.


manfred

Re: [linux-lvm] mount root filesystem on lvm

[Manfred Gschweidl]

hello once again,

i used the ls command within the "linuxrc" script of the initial ramdisk.
"ls /dev/mapper/control" results only with "/dev/mapper/control"

"ls /dev/mapper results in following output:
control
...
progs-root
...

so i used "root=/dev/mapper/progs-root" as boot option, but i can still 
not mount the root filesystem.

was anyone successfull with booting the root-filesystem on am lvm-volume 
with lvm2 and device-mapper interface, using an initial ramdisk??

can anyone point me in the right direction??


thanks for any help in advance.

greetings from austria,

manfred




Manfred Gschweidl wrote:
> 
> hello again,
> 
> now i solved the problems with "/dev/mapper/control".
> 
> it seems, that the kernel now finds all volumegroups, but now i get a 
> kernel panic, that the kernel cannot mount my root filesystem within the 
> lvm volumes. the message says, that i should append the correct "root=" 
> boot option on startup??
> 
> with kernel 2.4.12 and lvm 1.x it was "/dev/progs/root".
> now i use kernel 2.4.20 with device-mapper and lvm2.
> as with kernel 2.4.12 i use a inital ramdisk.
> 
> how can i find out, what now is the correct option for "root="??
> 
> 
> thanks for any help again.
> 
> 
> manfred
> 
> 
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> 

Re: [linux-lvm] mount root filesystem on lvm

[Christophe Saout]

Am Fre, 2003-05-09 um 21.19 schrieb Manfred Gschweidl:

> was anyone successfull with booting the root-filesystem on am lvm-volume 
> with lvm2 and device-mapper interface, using an initial ramdisk??
> 
> can anyone point me in the right direction??

I built my own ramdisk for that purpose (loosely based on the old LVM1
ramdisk). It's contains the following files:

-rwxr-xr-x  1 root root  442740 Dec 13 00:48 bin/bash
-rwxr-xr-x  1 root root   17196 Nov  7  2002 bin/mknod
-rwsr-xr-x  1 root root   60896 Jan 20  2002 bin/mount
-rwxr-xr-x  1 root root   46692 Nov  7  2002 bin/sed
-rwxr-xr-x  1 root root    4948 Dec 25 18:02 bin/true
-rwsr-xr-x  1 root root   27524 Jan 20  2002 bin/umount
-rw-r--r--  1 root root      66 Jan 11 17:17 etc/fstab
-rw-r--r--  1 root root   16932 Dec 12 23:36 etc/modprobe.conf
-rw-r--r--  1 root root      24 Jan 11 17:17 etc/mtab
-rwxr-xr-x  1 root root   91790 Nov  7  2002 lib/ld-linux.so.2
-rwxr-xr-x  1 root root 1193240 Nov  7  2002 lib/libc.so.6
-rwxr-xr-x  1 root root   17300 Nov  7  2002 lib/libdevmapper.so.0.96
-rwxr-xr-x  1 root root    9140 Nov  7  2002 lib/libdl.so.2
-rwxr-xr-x  1 root root   23256 Dec 12 23:56 lib/libhistory.so.4
-rwxr-xr-x  1 root root  289484 Jan 20  2002 lib/libncurses.so.5
-rwxr-xr-x  1 root root  156144 Dec 13 00:39 lib/libreadline.so.4
-r-xr-xr-x  1 root root     433 Dec 25 18:24 linuxrc
-rwxr-xr-x  1 root root    5876 Jan 11 17:15 sbin/insmod
-r-xr-xr-x  1 root root  329956 Jan 11 17:13 sbin/lvm
-rwxr-xr-x  1 root root   18556 Jan 11 17:15 sbin/modprobe

Note: I'm using kernel 2.5.69, so instead of modprobe.conf you should
use modules.conf, the only purpose of this file in conjunction with
modprobe is to suppress a lot of kernel messages that say it couldn't
load the module for major blabla). The shared libraries were used by my
bash, you can check that with ldd.

The shell script /linuxrc looks like this (note: I removed the
indentation to fit everything into one line, you might want to correct
this):

#!/bin/sh
/bin/mount /proc
echo /sbin/modprobe > /proc/sys/kernel/modprobe
if test ! -e /dev/.devfsd ; then
set -e
MAJOR=$(/bin/sed -n 's/^ *\([0-9]\+\) \+misc$/\1/p' /proc/devices)
MINOR=$(/bin/sed -n 's/^ *\([0-9]\+\) \+device-mapper$/\1/p' /proc/misc)
if test -n "$MAJOR" -a -n "$MINOR" ; then
    /bin/mknod --mode=600 /dev/mapper/control c $MAJOR $MINOR
fi
fi
/sbin/lvm vgchange --ignorelockingfailure -a y
/bin/umount /proc

The other text files contain this:

chtephan:/mnt/tmp # cat etc/mtab
/dev/ram0 / ext2 rw 0 0
chtephan:/mnt/tmp # cat etc/fstab
/dev/ram0       /               ext2    defaults        0   0
proc            /proc           proc    defaults        0   0

You can also find this ramdisk under
http://www.saout.de/misc/initrd-2.5.67-lvm2-athlon.gz - as the name
suggets my libc is athlon optimized, so you might want to replace some
libraries or executables.

BTW: I've also got some lilo patches on that page (remove the filename
after the last slash) that make it recognize device-mapper volumes.

-- 
Christophe Saout <christophe@saout.de>

Re: [linux-lvm] mount root filesystem on lvm

[Manfred Gschweidl]

hello,

thanks for your response. ;-)

i have one more question: what does your "lilo.conf" look like???
especially the "root=...." parameter ist he most interesting one. how 
does it need to be named with device-mapper???

thanks for any reply again,


manfred





Christophe Saout wrote:
> Am Fre, 2003-05-09 um 21.19 schrieb Manfred Gschweidl:
> 
> 
>>was anyone successfull with booting the root-filesystem on am lvm-volume 
>>with lvm2 and device-mapper interface, using an initial ramdisk??
>>
>>can anyone point me in the right direction??
> 
> 
> I built my own ramdisk for that purpose (loosely based on the old LVM1
> ramdisk). It's contains the following files:
> 
> -rwxr-xr-x  1 root root  442740 Dec 13 00:48 bin/bash
> -rwxr-xr-x  1 root root   17196 Nov  7  2002 bin/mknod
> -rwsr-xr-x  1 root root   60896 Jan 20  2002 bin/mount
> -rwxr-xr-x  1 root root   46692 Nov  7  2002 bin/sed
> -rwxr-xr-x  1 root root    4948 Dec 25 18:02 bin/true
> -rwsr-xr-x  1 root root   27524 Jan 20  2002 bin/umount
> -rw-r--r--  1 root root      66 Jan 11 17:17 etc/fstab
> -rw-r--r--  1 root root   16932 Dec 12 23:36 etc/modprobe.conf
> -rw-r--r--  1 root root      24 Jan 11 17:17 etc/mtab
> -rwxr-xr-x  1 root root   91790 Nov  7  2002 lib/ld-linux.so.2
> -rwxr-xr-x  1 root root 1193240 Nov  7  2002 lib/libc.so.6
> -rwxr-xr-x  1 root root   17300 Nov  7  2002 lib/libdevmapper.so.0.96
> -rwxr-xr-x  1 root root    9140 Nov  7  2002 lib/libdl.so.2
> -rwxr-xr-x  1 root root   23256 Dec 12 23:56 lib/libhistory.so.4
> -rwxr-xr-x  1 root root  289484 Jan 20  2002 lib/libncurses.so.5
> -rwxr-xr-x  1 root root  156144 Dec 13 00:39 lib/libreadline.so.4
> -r-xr-xr-x  1 root root     433 Dec 25 18:24 linuxrc
> -rwxr-xr-x  1 root root    5876 Jan 11 17:15 sbin/insmod
> -r-xr-xr-x  1 root root  329956 Jan 11 17:13 sbin/lvm
> -rwxr-xr-x  1 root root   18556 Jan 11 17:15 sbin/modprobe
> 
> Note: I'm using kernel 2.5.69, so instead of modprobe.conf you should
> use modules.conf, the only purpose of this file in conjunction with
> modprobe is to suppress a lot of kernel messages that say it couldn't
> load the module for major blabla). The shared libraries were used by my
> bash, you can check that with ldd.
> 
> The shell script /linuxrc looks like this (note: I removed the
> indentation to fit everything into one line, you might want to correct
> this):
> 
> #!/bin/sh
> /bin/mount /proc
> echo /sbin/modprobe > /proc/sys/kernel/modprobe
> if test ! -e /dev/.devfsd ; then
> set -e
> MAJOR=$(/bin/sed -n 's/^ *\([0-9]\+\) \+misc$/\1/p' /proc/devices)
> MINOR=$(/bin/sed -n 's/^ *\([0-9]\+\) \+device-mapper$/\1/p' /proc/misc)
> if test -n "$MAJOR" -a -n "$MINOR" ; then
>     /bin/mknod --mode=600 /dev/mapper/control c $MAJOR $MINOR
> fi
> fi
> /sbin/lvm vgchange --ignorelockingfailure -a y
> /bin/umount /proc
> 
> The other text files contain this:
> 
> chtephan:/mnt/tmp # cat etc/mtab
> /dev/ram0 / ext2 rw 0 0
> chtephan:/mnt/tmp # cat etc/fstab
> /dev/ram0       /               ext2    defaults        0   0
> proc            /proc           proc    defaults        0   0
> 
> You can also find this ramdisk under
> http://www.saout.de/misc/initrd-2.5.67-lvm2-athlon.gz - as the name
> suggets my libc is athlon optimized, so you might want to replace some
> libraries or executables.
> 
> BTW: I've also got some lilo patches on that page (remove the filename
> after the last slash) that make it recognize device-mapper volumes.
> 

Re: [linux-lvm] mount root filesystem on lvm

[Christophe Saout]

Am Sam, 2003-05-10 um 18.02 schrieb Manfred Gschweidl:

> i have one more question: what does your "lilo.conf" look like???
> especially the "root=...." parameter ist he most interesting one. how 
> does it need to be named with device-mapper???

It looks fairly simple:

boot    = /dev/hda
vga     = normal
read-only
lba32
prompt
timeout = 30
message = /boot/message

image  = /boot/vmlinuz
  label  = linux
  root   = /dev/mapper/vg-root
  initrd = /boot/initrd

But I think you can also use /dev/vg/root (in my case). I think lilo
only uses this line to look up the device number (major, minor).

What's your problem?

-- 
Christophe Saout <christophe@saout.de>

Re: [linux-lvm] mount root filesystem on lvm

[Manfred Gschweidl]

the kernel always complaines, that he cannot mount the root fs...

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

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

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....

i want to upgrade from 2.4.12 LVM1 to 2.4.20 LVM2....
booting with 2.4.12 and LVM1 works now for nearly 2 years.

thanks again,

manfred



Christophe Saout wrote:
> Am Sam, 2003-05-10 um 18.02 schrieb Manfred Gschweidl:
> 
> 
>>i have one more question: what does your "lilo.conf" look like???
>>especially the "root=...." parameter ist he most interesting one. how 
>>does it need to be named with device-mapper???
> 
> 
> It looks fairly simple:
> 
> boot    = /dev/hda
> vga     = normal
> read-only
> lba32
> prompt
> timeout = 30
> message = /boot/message
> 
> image  = /boot/vmlinuz
>   label  = linux
>   root   = /dev/mapper/vg-root
>   initrd = /boot/initrd
> 
> But I think you can also use /dev/vg/root (in my case). I think lilo
> only uses this line to look up the device number (major, minor).
> 
> What's your problem?
> 

Re: [linux-lvm] mount root filesystem on lvm

[Christophe Saout]

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.

-- 
Christophe Saout <christophe@saout.de>

Re: [linux-lvm] mount root filesystem on lvm

[Manfred Gschweidl]

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.
> 

Re: [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.
>>
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> 

Re: [linux-lvm] mount root filesystem on lvm

[Christophe Saout]

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. ;-)

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.

-- 
Christophe Saout <christophe@saout.de>

Re: [linux-lvm] mount root filesystem on lvm

[Manfred Gschweidl]

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,

manfred

Re: [linux-lvm] mount root filesystem on lvm

[Christophe Saout]

Am Son, 2003-05-11 um 21.38 schrieb Manfred Gschweidl:

> 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.

Ah, ok, I'm seeing. Well, I think that's a problem with LVM2. At the
moment the device files are created either when a volume group gets
activated or when it is already active and you add a logical volume.

But when the volume group got activated by the ramdisk and the system
switches the root filesystem, you now don't have the devices files.

I think that's where "lvm mknodes" should kick it, but... not
implemented yet. And you can't deactivate and reactivate the volume
group because the root filesystem on it is mounted.

Great. :D

So it looks like you must create the device files manually.

cd /dev/mapper
mknod volumegroupname-logicalvolumename b 254 0
mknod volumegroupname-logicalvolumename b 254 1
...

After that you also should create the symlinks

cd /dev/volumegroupname
ln -s ../mapper/volumegroupname-logicalvolumename logicalvolumename
...

Since you already put an ls command into the ramdisk before you should
know which minor got assigned to which volume.

Or, perhaps this should work: AFAIK if you have a directory /initrd on
your root filesystem, the old ramdisk should be moved there after the
root filesystem is mounted, so you can just copy the directories and
device files that got create there in /dev (/initrd/dev/mapper and
/initrd/dev/volumegroupname) to your /dev. But I have never tested this.

This sounds rather ugly and complicated, but it only occurs when
switching from LVM1 to LVM2 while having it mounted (because you can't
activate it via LVM2 while running on the real filesystem where the
device nodes should be created correctly. Or wait until the mknodes
command is finished or implement it yourself. ;-)

-- 
Christophe Saout <christophe@saout.de>

Re: [linux-lvm] mount root filesystem on lvm

[Manfred Gschweidl]

thanks for your help.

after more than one week, now my system boots cleanly without problems, 
and everything is ok now.

greetings from austria,

manfred





Christophe Saout wrote:
> Am Son, 2003-05-11 um 21.38 schrieb Manfred Gschweidl:
> 
> 
>>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.
> 
> 
> Ah, ok, I'm seeing. Well, I think that's a problem with LVM2. At the
> moment the device files are created either when a volume group gets
> activated or when it is already active and you add a logical volume.
> 
> But when the volume group got activated by the ramdisk and the system
> switches the root filesystem, you now don't have the devices files.
> 
> I think that's where "lvm mknodes" should kick it, but... not
> implemented yet. And you can't deactivate and reactivate the volume
> group because the root filesystem on it is mounted.
> 
> Great. :D
> 
> So it looks like you must create the device files manually.
> 
> cd /dev/mapper
> mknod volumegroupname-logicalvolumename b 254 0
> mknod volumegroupname-logicalvolumename b 254 1
> ...
> 
> After that you also should create the symlinks
> 
> cd /dev/volumegroupname
> ln -s ../mapper/volumegroupname-logicalvolumename logicalvolumename
> ...
> 
> Since you already put an ls command into the ramdisk before you should
> know which minor got assigned to which volume.
> 
> Or, perhaps this should work: AFAIK if you have a directory /initrd on
> your root filesystem, the old ramdisk should be moved there after the
> root filesystem is mounted, so you can just copy the directories and
> device files that got create there in /dev (/initrd/dev/mapper and
> /initrd/dev/volumegroupname) to your /dev. But I have never tested this.
> 
> This sounds rather ugly and complicated, but it only occurs when
> switching from LVM1 to LVM2 while having it mounted (because you can't
> activate it via LVM2 while running on the real filesystem where the
> device nodes should be created correctly. Or wait until the mknodes
> command is finished or implement it yourself. ;-)
>