LVM versus parted
 

I can see the advantages of LVM in some situations, such as joining a bunch of disks together into one big partition, and allowing snapshots of the partition (ideal for long tape dumps), but I don't see how it buys me much for allocating space on a single disk, despite that argument in the HOWTO for it.

Here's the specifics. I have a 40GB system disk. Suppose I divide it foolishly, giving roughly 10GB each to /, /usr, /var and /opt. (Ignore /boot and swap). Say I later discover that I need more space in /var and that /opt is mostly empty.

Scenario A, using LVM: I boot to single-user mode, or maybe I boot off a rescue disk, and use LVM to resize the /var and /opt partitions. I use resize2fs to resize the filesystems that live in those partitions. I reboot and hope that all is well. Right?

Scenario B, using old-fashioned partitions: I boot to single-user mode or boot off a rescue disk. I use parted to resize and move the /var and /opt partitions. I reboot and hope that all is well. Right?

Assuming I got the two scenarios right (a long shot, but that's my understanding from reading various HOWTOs), what is LVM buying me? I still have to shut the machine down, which is a hassle for my users. The operations don't seem to be any easier. Finally, with LVM, there are all kinds of dire warnings about not using it for / and /boot, so I still have some old-fashioned partitions (not that that's necessarily bad).

So, why would I go to the extra effort to use LVM?

Thanks very much for any advice or pointers.

Scott