Just in case you did not know about that, I spent some minutes today figuring out how to resize a LVM logical volume there are snapshots of it: the volume cannot be active. This is a pity if your root filesystem is inside a logical volume. Fortunately, you can stop the bootup process of recent Debian installations in the initial RAM disk by passing break=mount; unfortunately this minimal system has the vgchange tool (needed to start/stop volumes) but it does not have lvresize (guess what it is needed for?).

Finally I ended up firing up the bootup process from a Debian “netinstall” CD, entered rescue in the bootloader prompt and switched to the second console just after the installer detects hardware and before it mounts disks. Then it was only a matter of typing:

 # vgchange -an vg
 # lvresize -L +300M vg/base

Then reboot the installed system and make the XFS filesystem grow with:

 # xfs_growfs /

…and you are done :)