When installing Debian, or a derivative OS such as crunchbang, you may have opted to separate out your partitions/logical volumes to manage your disk space more finely.

I opted to do this.  My partitions were set up thus:

$ sudo lvs 

 LV     VG   Attr     LSize   
 home   t420 -wi-ao-- 438.10g 
 root   t420 -wi-ao-- 332.00m 
 swap_1 t420 -wi-ao-- 15.50g     <-- way too big!
 tmp    t420 -wi-ao-- 369.00m    <-- way too small!
 usr    t420 -wi-ao-- 8.38g 
 var    t420 -wi-ao-- 2.79g

This was not working for me.  Doing backups using the easy backintime was proving difficult, as backintime relied on more /tmp space than I had.

As I rarely touched swap space, I figured that 15.5G was probably a bit large for my needs.  Thankfully, nabbing swap space and reusing it for the filesystem is easy as pie – and all achieved with no downtime.

Here’s the sequence I typed into a terminal.  First, turn off swap:

$ sudo swapoff -a

Then resize the swap volume:

$ sudo lvresize -L 8GB /dev/t420/swap_1

Now re-format the swap partition before using it again:

$ sudo mkswap /dev/t420/swap_1

Then turn swap availability back on:

$ sudo swapon -a

And finally, resize the /tmp partition on-the-fly:

$ sudo lvextend -L +1G -r -v /dev/t420/tmp

Because the LVM tools have semi-awareness with respect to filesystems, the resizing of /tmp (using the -r switch) was achieved on-line – no need to log out, reboot or anything else.  The verbose (-v) switch allowed me to see everything that was happening.

The new partition sizing is:

 LV     VG   Attr     LSize 
 home   t420 -wi-ao-- 438.10g 
 root   t420 -wi-ao-- 332.00m 
 swap_1 t420 -wi-ao-- 8.00g 
 tmp    t420 -wi-ao-- 1.37g 
 usr    t420 -wi-ao-- 8.38g 
 var    t420 -wi-ao-- 2.79g

I also have 6.5G spare on the hard drive now, in case it’s needed by another logical volume.

LVM rocks for easy filesystem management!  Try it out!