undo LVM?

[Dave Howorth]

Herman Aalderink wrote:
> On Thu, 2010-05-06 at 11:38 +0100, Dave Howorth wrote:
>> Herman Aalderink wrote:
>>  > hermanbb at tabang1:~$ sudo lvdisplay
>>> hermanbb at tabang1:~$ sudo lvdisplay
>>> hermanbb at tabang1:~$ 
>>>
>>> hermanbb at tabang1:~$ sudo lvscan
>>> hermanbb at tabang1:~$ sudo lvscan
>>> hermanbb at tabang1:~$ 
>>>
>>> I dont get a response with either cmd.
>> Herman, am I right in thinking that you have previously used these LVM
>> volumes and you believe they have data in them? If so, the following
>> might help.
> 
> This is the first time I heard the term 'lvm'.
> This is the first time I used lvm in my system.
>  'lvm' came up when installing Ubuntu 10.04LTS Alternate 64-bit.
>  (I thought it was about 'Linear Addressing' of large harddisks as I
> used to do in the BIOS, LBA?)

Ah, OK. That makes the problem much simpler and easier. Ignore my
previous suggestion then.

> lvm was never asked to make a change or adjustment.
>  (lvm was never activated beyond the initial installation)
> Yes, the /HOME I am after is the my /HOME prior to lvm-install.

> Luis/Dave: I still have a lot of 'lvm-studying' to do.
> 
> My question is: What does lvm do when installed?
> -lvm changes the first sector(?) on every partition.
>   (can this be reversed?)
>   As is, no program or OS recognizes (the partition as partition),
> except a partition-editor.
> -does lvm alter the FAT upon installation? Can this be reversed?
> -what else does lvm alter?

LVM takes over the partitions that you assign to it, which it calls
physical volumes. You collect these into one or more 'volume groups' -
you've got exactly one, called 'hill60'. Then you create virtual
partitions, which it calls 'logical volumes' inside those and finally
you create normal filesystems in the logical volumes.

LVM stores its own control data plus your filesystem data in the
partitions. You don't really need to worry about how exactly - I don't
know, for example.

I find LVM is very useful because you can change filesystem sizes later.
You can add a new disk to your system, give it to LVM as a new physical
volume and then use its space to extend an existing filesystem, for
example. So you never need to worry about running out of space.

Your installation seems to have just stopped part way through. It
doesn't seem to be broken. It's created the physical volumes and the
volume group but not the logical volumes or any filesystems. So you can
just continue the creation, if you wish. You can create a logical volume
called say 'lv_home' and format it as ext3 or whatever and it will
appear as /dev/hill60/lv_home and you can mount it on /home. You can
create LVs for /usr and /var and /tmp and whatever else you like
(/media/video perhaps?)

On the other hand, if you decide not to use LVM and you want to remove
it, you just reformat the partitions with whatever format you want to use.

Cheers, Dave