[linux-lvm] Cannot unmount logical volume to reduce it

[linux-lvm] Cannot unmount logical volume to reduce it

[Dan White]

RHEL5.7 x86_64
I want to reduce the size of the logical volumes on a server.
The two giving me trouble are mounted on /var and /usr

I cannot unmount them to reduce them.  Even tried booting into a rescue disc.

Any suggestions ?

“Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.”
Bill Waterson (Calvin & Hobbes)

Re: [linux-lvm] Cannot unmount logical volume to reduce it

[Joe Pruett]

when you use the rescue disk, you need to tell it to skip the mounting
of the drives.  and i hope you know that you need to shrink the file
system first before you reduce the lv.  i don't know if the appropriate
tools will be available on the rescue disk without mounting the main
system drive, though.  using a livecd might be needed.

On 11/08/2011 10:00 AM, Dan White wrote:
> RHEL5.7 x86_64
> I want to reduce the size of the logical volumes on a server.
> The two giving me trouble are mounted on /var and /usr
>
> I cannot unmount them to reduce them.  Even tried booting into a rescue disc.
>
> Any suggestions ?
>
> “Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.”
> Bill Waterson (Calvin & Hobbes)
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>

Re: [linux-lvm] Cannot unmount logical volume to reduce it

[Dan White]

Thanks.  I'll try it and see what I get.
I may be able to customize a rescue disc.

----- Joe Pruett <joey@q7.com> wrote:
> when you use the rescue disk, you need to tell it to skip the mounting
> of the drives.  and i hope you know that you need to shrink the file
> system first before you reduce the lv.  i don't know if the appropriate
> tools will be available on the rescue disk without mounting the main
> system drive, though.  using a livecd might be needed.
> 
> On 11/08/2011 10:00 AM, Dan White wrote:
> > RHEL5.7 x86_64
> > I want to reduce the size of the logical volumes on a server.
> > The two giving me trouble are mounted on /var and /usr
> >
> > I cannot unmount them to reduce them.  Even tried booting into a rescue disc.
> >
> > Any suggestions ?

“Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.”
Bill Waterson (Calvin & Hobbes)

Re: [linux-lvm] Cannot unmount logical volume to reduce it

[Dan White]

Thanks Joe.  That was a great suggestion.

Here's what I did (for the benefit of others trying to do this):

Boot into the rescue CD, did NOT mount the file systems.

At the prompt:
    lvm vgscan

This created /dev/volgrp01

Then:
    lvm vgchange -ay

This created /dev/volgrp01/usrVol /dev/volgrp01/varVol etc

These are the volume group and logical group names I gave the original OS installation.

Then, using /dev/volgrp01/usrVol as an example, to be resized to 10 gigabytes:
    e2fsck -pvf /dev/volgrp01/usrVol
    resize2fs -f /dev/volgrp01/usrVol 10g
    lvm lvresize -v -L 10g /dev/volgrp01/usrVol

The system warns and whines aboiut the last step, but I did not mess up my file systems.

“Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.”
Bill Waterson (Calvin & Hobbes)

----- Joe Pruett <joey@q7.com> wrote:
> when you use the rescue disk, you need to tell it to skip the mounting
> of the drives.  and i hope you know that you need to shrink the file
> system first before you reduce the lv.  i don't know if the appropriate
> tools will be available on the rescue disk without mounting the main
> system drive, though.  using a livecd might be needed.
> 
> On 11/08/2011 10:00 AM, Dan White wrote:
> > RHEL5.7 x86_64
> > I want to reduce the size of the logical volumes on a server.
> > The two giving me trouble are mounted on /var and /usr
> >
> > I cannot unmount them to reduce them.  Even tried booting into a rescue disc.
> >
> > Any suggestions ?
> >
> > “Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.”
> > Bill Waterson (Calvin & Hobbes)
> >
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm@redhat.com
> > https://www.redhat.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> >
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] Cannot unmount logical volume to reduce it

[James Hawtin]

Dan White wrote:
> Thanks.  I'll try it and see what I get.
> I may be able to customize a rescue disc.
>   
IF you don't mount the disks, you may need to so a pvscan and a vgchange 
-a y

the other alturnative when you use a rescue disk is to just inmount the 
filesystems, you will not have a problem as the disks are not in use.

The third alturnative is to take out the disks from the fstab, and use 
grub to boot the machine single user however, newer OS like centos 6 
will not like this rather than dropping to a shell will just throw a 
wobbly and reboot.

James