x86_64: I was fooled when installing over existing LVM (Breezy)

[Eric S. Johansson]

Alan E. Davis wrote:
> My new amazing machine w/ x86_64 FC3 Fedora installed from the factory.  
> I have been wrestling with that beast with a shabby connection at 
> school, and finally decided to install ubuntu breezy live preview so I 
> can get something done.  The factory had installed w/ LVM, one Volume 
> Group subsumes two hdd.  I thought I'd try to play with LVM and shrink 
> it, so I can make a partition to install UBUNTU into.  I know I was in 
> over my head, but I have to say, Ubuntu allowed me to exercise my 
> freedom, and trash the whole LVM setup.  Which is cool, I guess, and I 
> know I deserved it.

unfortunately, acquiring scar tissue is the order of the day.  And as 
they say, your purpose in life may be to serve as an example to others.


> Now I have found a WWW page that suggests using qtparted from Knoppix to 
> partition before installing Ubuntu.  Is anybody listening?  Would that 
> have made a difference? 

I don't believe so. disk repartitioning software is sort of a poor man's 
logical volume manager.  You take the system off-line, you add new 
partitions and then do your installation etc.  For 90% of the cases, it 
works fine.  But in your case, with LVM already installed and merging to 
disks into one logical volume, you did the right thing trying to use LVM 
and it should have worked.  The problem was shrinking partitions is that 
you also need to run a filesystem resizer before you shrink the logical 
volume.

Think about it.  the logical volume manager only manages the size of the 
storage.  The filesystem resizer manages the size of the filesystem 
within that storage.  So the right thing would have been to shrink the 
filesystem to the size of the partition you desired and then shrink the 
logical volume.

Now I will admit I haven't done this filesystem/partition shrinking bit 
on linux yet but I do have years experience with filesystems in a 
previous life.  The question in my mind is whether or not there is a 
nice way of shrinking a filesystem then partition so that the two don't 
have the waste space between them.  As you've learned, there are no 
protections when the LVM partition is smaller than the filesystem so 
this probably nothing on the other side either.

obviously, this is one of the regions where Linux needs better human 
factors.

--- eric