On Fri, 2005-03-11 at 11:04 -0500, Chris Lumens wrote:
> First, it frees us from a lot of the disklabel constraints. We don't
> really have to worry about four partition limits and extended partitions
> and all that junk if we can just make one big LVM blob and cram a bunch
> of partitions in there. So that makes it more flexible for people who
> want the really crazy partitioning schemes.
Yeah, that's a useful property, but even without details of how
partition tables work and whatnot, there's a huge advantage. I think the
biggest gain is that it largely obviates the need to move files around
when you're adding disks. That is, the old scenario is:
/home fills up
add disk
boot single user
fdisk
mke2fs /dev/hdz1
mount /dev/hdz1 /tmp/home/
cp -avl /home/ /tmp/home/
wait several hours
backup /home someplace else
wait several hours
rm -r /home/
umount /tmp/home/
fix fstab
mount /home
telinit 3
Whereas with lvm the script is more like:
/home fills up
add disk
boot single user
fdisk
pvcreate /dev/hdz1
vgextend /dev/VolGroup00
mount / -o remount,ro
lvextend -i 250g -r /dev/VolGroup00/LogVol01
mount / -o remount,rw
telinit 3
(I haven't tried it this week, and obviously I've left out lots of minor
details, but that's essentially the method)
Not having to move files around is obviously a significant gain.
--
Peter
