Use LVM2 to expand volumes on the fly.

Logical volumes are easy to extend. The basic steps are like this:

1. check free space
2. expand logic volume
3. expand file system.

With lvm2 you can do it even with file system mounted.

Although I recommend to make a backup first and switch to single user mode if it is a server.

Here’s the recipe:

1. Check the mounted file system with

df -h

2. Check the available logic volumes

sudo lvdisplay

3. Check how much free space available in this volume group for the growth

sudo vgdisplay

4. Now resize the logic volume up to some point (of course within the free space limit)

sudo lvresize -L +1GB /dev/mapper/vg-xxx/yyy

5. Check the new size of the logic volume

sudo lvdisplay

6. Expand the existing file system to the size of logic volume

sudo resize2fs -p /dev/mapper/vg-xxx/yyy

This command works for both ext2 and ext3 file systems.