[linux-lvm] missing device nodes for vg, but vg appears in scan

[Geoff Mishkin]

Hi, and thanks for the response.  Unfortunately it is still not working.  For 
completeness, I have:

device-mapper: 4.4.0-ioctl (2005-01-12) (Kernel)
device-mapper 1.01.03 (Userspace)


On Saturday 11 February 2006 09:19 pm, Zac Slade wrote:
> On Sunday 22 January 2006 13:53, Geoff Mishkin wrote:
> > I am using lvm2 2.01.09 on Gentoo Linux.  My kernel version is 2.6.15 and
> > I'm using udev 079.
>
> I'm running 2.6.15 also using lvm
>
> > I am trying to set up an LVM2 VG using a loop device.  My problem is that
> > device nodes are never created for my VG.  However, my VG shows up in
> > scans (vgscan) and displays (vgdisplay).  Even vgscan --mknodes does not
> > make the nodes.  Because I never get a node for my VG, I can't figure out
> > how I am supposed to create LV's in it.
>
> First make sure that /etc/lvm/lvm.conf is not filtering out /dev/loop/
> devices.  Based on the ouput you gave from pvcreate I guess that it isn't,
> but you should double check anyway.  Also read through the options in that
> file one might jump out at you.
>
I checked this and it is fine.  No other options jump out at me.

> > I have the modules loop, dm-mod and dm-snapshot loaded.  Therefore, I do
> > have /dev/mapper/control.  Here is what I have done so far:
>
> dm-mod is the only required module.  Well and loop for your set up.
>
Okay well I suppose I'd need dm-snapshot eventually if I ever get this part 
working. :)

> > It looks like my VG is there, but it still isn't showing up in /dev.  I
> > read something about how if udev isn't configured properly, you will get
> > devices like /dev/dm-# where # is 0-9, instead of named VG nodes.  I
> > don't have those either, but I follow the instructions which are to
> > uncomment a line in my udev rules:
> >
> > KERNEL=="dm-[0-9]*",    PROGRAM="/sbin/devmap_name %M %m", NAME="%k",
> > SYMLINK+="%c"
>
> I looked at my /etc/udev/rules.d/50-udev.rules and I have the following:
> # dm devices (ignore them)
> KERNEL=="dm-[0-9]*",    OPTIONS="ignore_device"
> # create a symlink named after the device map name
> # note devmap_name comes with extras/multipath
> #KERNEL=="dm-[0-9]*",   PROGRAM="/sbin/devmap_name %M %m", NAME="%k",
> SYMLINK+="%c"
> KERNEL=="device-mapper",        NAME="mapper/control"
>
Now this is interesting.  So you say that you have working volume groups on 
loop devices?  But you still have the "ignore_device" option active.  So I 
went backed and switched this in my udev rules but it still didn't work.

> I'm just not sure why they aren't getting created.  Even without vgscan you
> should get the devices if you are using udev.  Maybe you upgraded udev and
> zapped the new rules during and etc-update or dispatchconf.

I'm pretty careful about doing etc-update, and that section of my udev rules 
now looks the same as yours.  Is there anything else specific you think the 
problem could be?

			--Geoff Mishkin <gmishkin at bu.edu>
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