[linux-lvm] Moving space between logical volumes?

[Meadows, Howard T]

Chris,

    Thanks for your reply. The logical volumes in question are ext3
filesystems. I did read the man page for lvreduce and its warning about
possible loss of data was what originally prompted me to ask for help.

    I do not want to resize the partition (they are all on the same
partition), so I am wondering if e2fsadm might do the trick? It looks like
you can shrink (and expand) logical volumes using e2fsadm with the
restriction that shrinking only works on unmounted filesystems (if I'm
reading the man page correctly). So... my current thought is as follows:

    * unmount the filesystems in question.
    * use 'tune2fs -O ^has_journal /dev/sda5' to turn off journaling
    * use 'e2fsadm -L -100G /dev/vg/lv1' to reduce lv1 by 100GB
    * use 'e2fsadm -L +100G /dev/vg/lv2' to increase lv2 by 100GB
    * use 'e2fsck -f /dev/sda5' to check the filesystems
    * use 'tune2fs -j /dev/sda5' to turn journaling back on
    * re-mount the filesystems

    It seems (from the man page for e2fsadm) that lvreduce/lvextend would
then not be needed. Is this true?

    I would like to feel more confident that this would actually work before
I jump in there and do it because I don't feel like looking for a new job if
it doesn't. ;-)

    Thanks,

-Howard
 

-----Original Message-----
From: linux-lvm-bounces at redhat.com [mailto:linux-lvm-bounces at redhat.com] On
Behalf Of Chris Osicki
Sent: Wednesday, August 31, 2005 4:28 PM
To: LVM general discussion and development
Subject: Re: [linux-lvm] Moving space between logical volumes?


Hi Howard

Your start point is "man lvreduce". Depending of the filesystem type
you're using you would have to find out how to resize the FS _before_
using lvreduce/lvextend. Depending on the FS type it may or may not be
possible to do it on a mounted FS. In worst case a boot from Rescue-CD
would be necessary == down-time.

You will have to do this:

	 resize (decrease size of) the file system on the huge_lvol
	 lvreduce huge_lvol
	 lvextend tight_lvol
	 resize (increase size of) the file system on the tight_lvol

LVols resizing was I think the first and most important motivation to
write LVM.
Good luck.

Regards,
Chris

On Wed, Aug 31, 2005 at 02:56:40PM -0500, Meadows, Howard T wrote:
> 
> I have a volume group with 4 logical volumes. One of the logical volumes
has
> a huge amount of space allocated to it, and another is running out of its
> space.
> 
> I am assuming there is a way to re-allocate space from the one with lots
of
> space to the one that is running out. I am nervous about using losing data
> with a reduce-extend combination of commands. Can someone who has done
this
> explain exactly how this is done (safely)?
> 
> Thanks,
> 
> -Howard
> 
> 
> =======================================================
> Howard Meadows                 howard-meadows at uiowa.edu
> ITS - SPA, Unix Systems Group              319-335-5519
> The University of Iowa                    Iowa City, IA
>  
> 



> _______________________________________________
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> linux-lvm at redhat.com
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> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

-- 

Chris Osicki osk at osk.ch
Dipl. Informatik-Ing. HTL

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