This realy helped my out. /var/cache/pacman took up over 5GB of space in my root partition. To prevent this from happening again, is there a way to move pacman cache to my home partition where I have over 300GB of space for pacman to consume?
I'm not currently using Arch so I can't test, but from this forum post it looks like you can change the CacheDir variable in /etc/pacman.conf to point anywhere you want.