lvrename changes link to direct /dev/dm-X

lvrename changes link to direct /dev/dm-X

[Oliver Rath]

Hi list,

I was able to reproduze the renaming issue on a gentoo-machine with lvm-git:

heimserver ~ # lvcreate --name myoriginal -V 10M -T dmivg/winthinpool
  Rounding up size to full physical extent 12,00 MiB
  Logical volume "myoriginal" created
heimserver ~ # ls -l /dev/dmivg/myoriginal
lrwxrwxrwx 1 root root 28 29. Aug 11:46 /dev/dmivg/myoriginal ->
/dev/mapper/dmivg-myoriginal
heimserver ~ # lvrename /dev/dmivg/myoriginal myrenamedoriginal
  Renamed "myoriginal" to "myrenamedoriginal" in volume group "dmivg"
heimserver ~ # ls -l /dev/dmivg/myrenamedoriginal
lrwxrwxrwx 1 root root 8 29. Aug 11:47 /dev/dmivg/myrenamedoriginal ->
../dm-13
heimserver ~ # ls -l /dev/mapper/dmivg-myrenamedoriginal
lrwxrwxrwx 1 root root 8 29. Aug 11:47
/dev/mapper/dmivg-myrenamedoriginal -> ../dm-13


It seems, that after renaming the link points directly to the /dev/dm-X
device, before that he linked to the link in /dev/mapper/..

In Ubuntu additionally there came an error-message "unable to rename ..."

The same in Ubuntu 12.04.03 with lvm-git:

root at asterisk:~# heimserver ~ # lvcreate --name myoriginal -V 10M -T
dmivg/winthinpool
heimserver: Befehl nicht gefunden.
root at asterisk:~# lvcreate --name myoriginal -V 10M -T dmivg/winthinpool
  Rounding up size to full physical extent 12,00 MiB
  Logical volume "myoriginal" created
root at asterisk:~# ls -l /dev/dmivg/myoriginal
lrwxrwxrwx 1 root root 28 Aug 29 11:50 /dev/dmivg/myoriginal ->
/dev/mapper/dmivg-myoriginal
root at asterisk:~# ls -l /dev/mapper/dmivg-myoriginal
lrwxrwxrwx 1 root root 8 Aug 29 11:50 /dev/mapper/dmivg-myoriginal ->
../dm-55
root at asterisk:~# lvrename /dev/dmivg/myoriginal myrenamedoriginal
  Renamed "myoriginal" to "myrenamedoriginal" in volume group "dmivg"
  Unable to rename device node from 'dmivg-myoriginal' to
'dmivg-myrenamedoriginal'
root at asterisk:~# ls -l /dev/dmivg/myrenamedoriginal
lrwxrwxrwx 1 root root 35 Aug 29 11:51 /dev/dmivg/myrenamedoriginal ->
/dev/mapper/dmivg-myrenamedoriginal
root at asterisk:~# ls -l /dev/mapper/dmivg-myrenamedoriginal
brw------- 1 root root 252, 55 Aug 29 11:51
/dev/mapper/dmivg-myrenamedoriginal
root at asterisk:~#

Here the device twice: in /dev/dm-55 _and_ in
/dev/mapper/dmivg-myrenamedoriginal

@Zdenek: if you need a -vvvv log, please tell me.

Tfh!
Oliver

lvrename changes link to direct /dev/dm-X

[Zdenek Kabelac]

Dne 29.8.2013 11:54, Oliver Rath napsal(a):
> Hi list,
>
> I was able to reproduze the renaming issue on a gentoo-machine with lvm-git:
>
> heimserver ~ # lvcreate --name myoriginal -V 10M -T dmivg/winthinpool
>    Rounding up size to full physical extent 12,00 MiB
>    Logical volume "myoriginal" created
> heimserver ~ # ls -l /dev/dmivg/myoriginal
> lrwxrwxrwx 1 root root 28 29. Aug 11:46 /dev/dmivg/myoriginal ->
> /dev/mapper/dmivg-myoriginal

So Gentoo has broken udev rules as well probably.
Links created by proper udev rules should be pointing directly to /dev/dm-x


Have you been compiling lvm2 yourself ?

Have you configured lvm2 package with --enable-udev_rules?
(it's not enabled by default)

Isn't there any udev falback running in this system ?

Isn't device activated without udev?

In pre-udev  era all dm nodes have been created in /dev/mapper subdir.
So lvm created links pointing to this place.

With  udev  all dm nodes are by default created as  /dev/dm-xx and all
the links in /dev/mapper & /dev/vgname/lvname  are pointing directly
to this node - but that require proper udev rules and properly configured 
system -  I'd recommend  to test with i.e. Fedora.

Unfortunately systems like Debian are using non-upstream udev rules
from maintainer which are reinventing them based on some unknown rules to us...


> heimserver ~ # lvrename /dev/dmivg/myoriginal myrenamedoriginal
>    Renamed "myoriginal" to "myrenamedoriginal" in volume group "dmivg"
> heimserver ~ # ls -l /dev/dmivg/myrenamedoriginal
> lrwxrwxrwx 1 root root 8 29. Aug 11:47 /dev/dmivg/myrenamedoriginal ->
> ../dm-13
> heimserver ~ # ls -l /dev/mapper/dmivg-myrenamedoriginal
> lrwxrwxrwx 1 root root 8 29. Aug 11:47
> /dev/mapper/dmivg-myrenamedoriginal -> ../dm-13
>
>
> It seems, that after renaming the link points directly to the /dev/dm-X
> device, before that he linked to the link in /dev/mapper/..

Well as long as the point to the proper device at the end - it's at least 
usable - but it's clear the udev dir has been probably touched by fallback 
rules (which are there for cases, udev is failing to do proper thing)


> root at asterisk:~# ls -l /dev/mapper/dmivg-myoriginal
> lrwxrwxrwx 1 root root 8 Aug 29 11:50 /dev/mapper/dmivg-myoriginal ->
> ../dm-55
> root at asterisk:~# lvrename /dev/dmivg/myoriginal myrenamedoriginal
>    Renamed "myoriginal" to "myrenamedoriginal" in volume group "dmivg"
>    Unable to rename device node from 'dmivg-myoriginal' to

Udev rules are not doing what they supposed to do....

> 'dmivg-myrenamedoriginal'
> root at asterisk:~# ls -l /dev/dmivg/myrenamedoriginal
> lrwxrwxrwx 1 root root 35 Aug 29 11:51 /dev/dmivg/myrenamedoriginal ->
> /dev/mapper/dmivg-myrenamedoriginal
> root at asterisk:~# ls -l /dev/mapper/dmivg-myrenamedoriginal
> brw------- 1 root root 252, 55 Aug 29 11:51
> /dev/mapper/dmivg-myrenamedoriginal
> root at asterisk:~#
>
> Here the device twice: in /dev/dm-55 _and_ in
> /dev/mapper/dmivg-myrenamedoriginal
>
> @Zdenek: if you need a -vvvv log, please tell me.

If you have been compiling lvm2 yourself - you could replace upstream rules 
with those placed in Debian.

I guess the only real solution here would be to build Debian package by some 
lvm2 team member since the package in Debian is probably broken.

Zdenek

lvrename changes link to direct /dev/dm-X

[Zdenek Kabelac]

Dne 30.8.2013 11:09, Zdenek Kabelac napsal(a):
> Dne 29.8.2013 11:54, Oliver Rath napsal(a):
>> Hi list,
>>
>> I was able to reproduze the renaming issue on a gentoo-machine with lvm-git:
>>
>> heimserver ~ # lvcreate --name myoriginal -V 10M -T dmivg/winthinpool
>>    Rounding up size to full physical extent 12,00 MiB
>>    Logical volume "myoriginal" created
>> heimserver ~ # ls -l /dev/dmivg/myoriginal
>> lrwxrwxrwx 1 root root 28 29. Aug 11:46 /dev/dmivg/myoriginal ->
>> /dev/mapper/dmivg-myoriginal
>
> So Gentoo has broken udev rules as well probably.
> Links created by proper udev rules should be pointing directly to /dev/dm-x
>
>
> Have you been compiling lvm2 yourself ?
>
> Have you configured lvm2 package with --enable-udev_rules?
> (it's not enabled by default)

Sorry - here should be   '--enable-udev_sync'
(And for built-in thin support you also need  '--with-thin=internal')

Zdenek

lvrename changes link to direct /dev/dm-X

[Oliver Rath]

Am 30.08.2013 11:12, schrieb Zdenek Kabelac:
> [..]
> Sorry - here should be   '--enable-udev_sync'
> (And for built-in thin support you also need  '--with-thin=internal')
>

A "./configure --help | grep udev" figured it out for me ;-)

Regards,
Oliver

lvrename changes link to direct /dev/dm-X

[Oliver Rath]

Hi Zdenek!

Am 30.08.2013 11:09, schrieb Zdenek Kabelac:
> [..]
> So Gentoo has broken udev rules as well probably.
> Links created by proper udev rules should be pointing directly to
> /dev/dm-x
>
>
> Have you been compiling lvm2 yourself ?

Yes, I compiled it myself. There is no ebuild for git at the moment.

>
> Have you configured lvm2 package with --enable-udev_rules?
> (it's not enabled by default)

No, I dont. Thank you for the hint. I will try that.

>
> Isn't there any udev falback running in this system ?

I dont know, what udev fallback is. Where do I have to look?

>
> Isn't device activated without udev?

AFAIK udev is always running. I can make a try generating lvm-devices
without a running udevd.


>
> In pre-udev  era all dm nodes have been created in /dev/mapper subdir.
> So lvm created links pointing to this place.
>
> With  udev  all dm nodes are by default created as  /dev/dm-xx and all
> the links in /dev/mapper & /dev/vgname/lvname  are pointing directly
> to this node - but that require proper udev rules and properly
> configured system -  I'd recommend  to test with i.e. Fedora.
ok
>
> Unfortunately systems like Debian are using non-upstream udev rules
> from maintainer which are reinventing them based on some unknown rules
> to us...
ok
>
>
>> heimserver ~ # lvrename /dev/dmivg/myoriginal myrenamedoriginal
>>    Renamed "myoriginal" to "myrenamedoriginal" in volume group "dmivg"
>> heimserver ~ # ls -l /dev/dmivg/myrenamedoriginal
>> lrwxrwxrwx 1 root root 8 29. Aug 11:47 /dev/dmivg/myrenamedoriginal ->
>> ../dm-13
>> heimserver ~ # ls -l /dev/mapper/dmivg-myrenamedoriginal
>> lrwxrwxrwx 1 root root 8 29. Aug 11:47
>> /dev/mapper/dmivg-myrenamedoriginal -> ../dm-13
>>
>>
>> It seems, that after renaming the link points directly to the /dev/dm-X
>> device, before that he linked to the link in /dev/mapper/..
>
> Well as long as the point to the proper device at the end - it's at
> least usable - but it's clear the udev dir has been probably touched
> by fallback rules (which are there for cases, udev is failing to do
> proper thing)

Yes, thats a point: it still useable. But these broken rules can create
really strange results of linking an, if you are using the link-names
semanticly like me, you can run into serious problem although.
>
>
>> root at asterisk:~# ls -l /dev/mapper/dmivg-myoriginal
>> lrwxrwxrwx 1 root root 8 Aug 29 11:50 /dev/mapper/dmivg-myoriginal ->
>> ../dm-55
>> root at asterisk:~# lvrename /dev/dmivg/myoriginal myrenamedoriginal
>>    Renamed "myoriginal" to "myrenamedoriginal" in volume group "dmivg"
>>    Unable to rename device node from 'dmivg-myoriginal' to
>
> Udev rules are not doing what they supposed to do....
Ok

>
>> 'dmivg-myrenamedoriginal'
>> root at asterisk:~# ls -l /dev/dmivg/myrenamedoriginal
>> lrwxrwxrwx 1 root root 35 Aug 29 11:51 /dev/dmivg/myrenamedoriginal ->
>> /dev/mapper/dmivg-myrenamedoriginal
>> root at asterisk:~# ls -l /dev/mapper/dmivg-myrenamedoriginal
>> brw------- 1 root root 252, 55 Aug 29 11:51
>> /dev/mapper/dmivg-myrenamedoriginal
>> root at asterisk:~#
>>
>> Here the device twice: in /dev/dm-55 _and_ in
>> /dev/mapper/dmivg-myrenamedoriginal
>>
>> @Zdenek: if you need a -vvvv log, please tell me.
>
> If you have been compiling lvm2 yourself - you could replace upstream
> rules with those placed in Debian.
Im using debian (ubuntu) rules at the moment. Will try your
upstream-rules by configuring --with-thin=internall --enable-udev_sync
--enable-udev_rules

>
> I guess the only real solution here would be to build Debian package
> by some lvm2 team member since the package in Debian is probably broken.

This would be a great thing because the actual lvm-packages are really,
really outdated.

I will give you report of my results.

Tfh!
Oliver