[linux-lvm] lvm on root filesystem with devfs

[linux-lvm] lvm on root filesystem with devfs

[Joe Harvell]

I made a custom initrd to bring up lvm on my root filesystem.  When not
running a kernel with devfs, I simply cpio the /dev entries from the ram
filesystem into the lvm root filesystem before doing pivot_root.  This
is so the remaining lvm filesystems can be mounted.  Everything works
fine in this case.

When I run with devfs, though, the /dev entries don't ever show up in
/dev when I do a vgscan.  The result is that I am not able to mount the
lvm root filesystem.


   * Does the fact that I have lvm compiled as a module have anything to
     do with this?
   * Assuming the entries are created, then I shouldn't have to use cpio
     anymore (with devfs).  Right?

---
Joe Harvell

RE: [linux-lvm] lvm on root filesystem with devfs

[Steve Wray]

> From: linux-lvm-admin@sistina.com [mailto:linux-lvm-admin@sistina.com]On
> Behalf Of Joe Harvell
[snip]
> When I run with devfs, though, the /dev entries don't ever show up in
> /dev when I do a vgscan.  The result is that I am not able to mount the
> lvm root filesystem.
> 
> 
>    * Does the fact that I have lvm compiled as a module have anything to
>      do with this?

uh huh. Unless;
1. the lvm module is on the initrd
and
2. the initrd loads this module

the lvm module will be on a logical volume which can't be mounted
because the kernel doesn't know how to...

Re: [linux-lvm] lvm on root filesystem with devfs

[Joe Harvell]

Yes, the lvm module is on the initrd.
Yes, the module is being loaded.

As I said, This works just fine if I am not using devfs.

Steve Wray wrote:

> > From: linux-lvm-admin@sistina.com [mailto:linux-lvm-admin@sistina.com]On
> > Behalf Of Joe Harvell
> [snip]
> > When I run with devfs, though, the /dev entries don't ever show up in
> > /dev when I do a vgscan.  The result is that I am not able to mount the
> > lvm root filesystem.
> >
> >
> >    * Does the fact that I have lvm compiled as a module have anything to
> >      do with this?
>
> uh huh. Unless;
> 1. the lvm module is on the initrd
> and
> 2. the initrd loads this module
>
> the lvm module will be on a logical volume which can't be mounted
> because the kernel doesn't know how to...
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html

Re: [linux-lvm] lvm on root filesystem with devfs

[Luca Berra]

On Fri, May 25, 2001 at 06:08:42PM -0500, Joe Harvell wrote:
> When I run with devfs, though, the /dev entries don't ever show up in
> /dev when I do a vgscan.  The result is that I am not able to mount the
> lvm root filesystem.
> 
> 
>    * Does the fact that I have lvm compiled as a module have anything to
>      do with this?
When you run with devfs device entries are not created by vgscan.
IIRC they should be created by the kernel whenever you activate the vg.

>    * Assuming the entries are created, then I shouldn't have to use cpio
>      anymore (with devfs).  Right?
right, the devfs mounted on your initrd is the same devfs that gets mounted
on /dev after pivot_root.

Regards,
L.

-- 
Luca Berra -- bluca@comedia.it
        Communication Media & Services S.r.l.
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