William John Murray wrote:
Hello all,
I just faced a laptop problem: How to shrink the FC4
allocated space in order to increase the space on another operating
system. I had used the default LVM.
A trusty knoppix liveCD QTparted knows nothing of LVM, so I tried the
FC4 rescue. After a long time, I found:
* resize2fs shrinks the ext3 / area. OK
* lvm lvreduce shrinks the logical volume (different units)
* lvm pvmove allows me to put all the lvm handled stuff physically
together. More different units.
* vgreduce...fails
I think I was supposed to use vgreduce to shrink the space managed in
the volume group - but I couldn't make it work. It only seems to delete
logical volumes.
Finally I reversed all the above operation. Since they are all in
different units, and I had padded a little to be safe, I had to pad
some more on the way back, and now I have wasted space.
Two questions:
*) How could I have made it work?
There is no straightforward way of shrinking an LVM physical volume that
I know of. I think you need to have some way of shifting all of the data
off that volume to somewhere else (e.g. backups, another disk), delete
the volume and then create a new, smaller one.
*) What benefit is there in lvm on a laptop, when you pretty much know
there will only be 1 disk?
In the default configuration of one big physical volume and one logical
volume for the whole system (exceot swap), there's not a lot of benefit.
However, if you configure it manually and use multiple volumes so as to
keep for instance the /, /var, /usr, /tmp, /home filesystems separate,
and/or you don't allocate all available disk space to the physical
volume, then LVM has benefits in that you can reallocate space usefully
later on. Just don't create a physical volume that you may need to
shrink in the future - it's better to create something too small and
then add to it when necessary,
Paul.
