LVM

#xfs(stable):

pvcreate /dev/sda
vgcreate SPEED /dev/sda
lvcreate -n node02 -L60G SPEED
lvcreate -n backup -L5T SLOW
lvextend -L+350G /dev/SPEED/node02
mount /dev/SPEED/node02 /var/lib/lxc/node02
xfs_growfs -d /var/lib/lxc/node02

#reiserfs (old good):

resize_reiserfs /dev/SPEED/node02

#create snapshot

lvcreate -L10G -s -n some-backup /dev/SPEED/some
mount /dev/SPEED/some-backup /mnt/some-backup

#remove snapshot

umount /mnt/some-backup
lvremove /dev/SPEED/some-backup